Over four decades of public life, Bill and Hillary Clinton have built an unrivaled global network of donors while pioneering fundraising techniques that have transformed modern politics and paved the way for them to potentially become the first husband and wife to win the White House.

The grand total raised for all of their political campaigns and their family’s charitable foundation reaches at least $3 billion, according to a Washington Post investigation.

Their fundraising haul, which began with $178,000 that Bill Clinton raised for his long-shot 1974 congressional bid, is on track to expand substantially with Hillary Clinton’s 2016 White House run, which has already drawn $110 million in support.

The Post identified donations from roughly 336,000 individuals, corporations, unions and foreign governments in support of their political or philanthropic endeavors — a list that includes top patrons such as Steven Spielberg and George Soros, as well as lesser-known backers who have given smaller amounts dozens of times. Not included in the count are an untold number of small donors whose names are not identified in campaign finance reports but together have given millions to the Clintons over the years.

The majority of the money — $2 billion — has gone to the Clinton Foundation, one of the world’s fastest-growing charities, which supports health, education and economic development initiatives around the globe. A handful of elite givers have contributed more than $25 million to the foundation, including Canadian mining magnate Frank Giustra, who is among the wealthy foreign donors who have given tens of millions.

Separately, donors have given $1 billion to support the Clintons’ political races and legal defense fund, making capped contributions to their campaigns and writing six-figure checks to the Democratic National Committee and allied super PACs.

The Post investigation found that many top Clinton patrons supported them in multiple ways, helping finance their political causes, their legal needs, their philanthropy and their personal bank accounts. In some cases, companies connected to their donors hired the Clintons as paid speakers, helping them collect more than $150 million on the lecture circuit in the past 15 years.

The couple’s biggest individual political benefactors are Univision chairman Haim Saban and his wife, Cheryl, who have made 39 contributions totaling $2.4 million to support the Clintons’ races since 1992. The Sabans have also donated at least $10 million to the foundation.

The Clintons kept big contributors in their orbit for decades by methodically wooing competing interest groups — toggling between their liberal base and powerful constituencies, according to donors, friends and aides who have known the couple since their Arkansas days.

They made historic inroads on Wall Street, pulling in at least $69 million in political contributions from the employees and PACs of banks, insurance companies, and securities and investment firms. Wealthy hedge fund managers S. Donald Sussman and David E. Shaw are among their top campaign supporters, having given more than $1 million each.

The Clintons’ ties to the financial sector strained their bonds with the left, particularly organized labor. But unions repeatedly shook off their disappointment, giving at least $21 million to support their races. The public employees union AFSCME has been their top labor backer, giving nearly $1.7 million for their campaigns.

The Clintons’ fundraising operation — $3 billion amassed by one couple, working in tandem for more than four decades — has no equal.

By comparison, three generations of the Bush family, America’s other contemporaneous political dynasty, have raised about $2.4 billion for their state and federal campaigns and half a dozen charitable foundations, according to a Post tally of their fundraising from 1988 through 2015 — even though the family has collectively held the presidency longer than the Clintons.

Both Clintons declined to be interviewed or comment for this article.

Josh Schwerin, a spokesman for Hillary Clinton, said campaign officials could not re-create The Post’s work to verify its findings.

“However, it should be noted that it would be misleading, at best, to conflate donations to a philanthropy with political giving,” Schwerin said in a statement. “And regarding the campaign contributions, the breadth and depth of their support is a testament to the fact that they have both dedicated their lives to public service and fighting to make this country stronger.”

The Clinton donor network is now serving as both a prime asset and liability for the former first lady, U.S. senator and secretary of state as she seeks the Democratic presidential nomination.

Her imposing resources helped scare off would-be Democratic rivals, such as Vice President Biden, and have positioned her well against her main challenger for the party nomination, Sen. Bernie Sanders (Vt.). By the end of September, Clinton had raised $35 million more than Sanders, and she had pulled in more than double the total collected so far by the top campaign fundraiser in the GOP field, retired neurosurgeon Ben Carson.

But in an election shaped by a mounting distaste for the influence of big money, Clinton’s long-standing ties to a cadre of wealthy patrons cuts against her efforts to cast herself as a champion of the middle class and a leader who will challenge the influence of large donors.

After Bill Clinton’s unsuccessful, labor-backed race for Congress, the couple hewed toward monied interests, courting banks and corporate leaders in Arkansas. It was a pattern that would repeat itself throughout their careers as they drew support from groups often in opposition: union leaders and corporate chiefs, trial lawyers and tech titans, top industrialists and liberal activists.

They have also been quick to seize on new sources of funds: Cuban Americans in Florida, Chinese immigrant communities in New York and wealthy figures around the world. And they have embraced bold new forms of fundraising, finding ways to inject corporate donations into political causes through nonprofit organizations in Arkansas and unregulated national party accounts.

Most of all, the Clintons have excelled at leveraging access to their power and celebrity. Following the advice of a young Democratic party finance chair named Terry McAuliffe, who is now governor of Virginia, the Clintons used the White House to entertain major donors. Perks included overnights in the Lincoln Bedroom. After leaving office, Bill Clinton headlined high-wattage gatherings for foundation donors around the globe. And supporters this year are jockeying to host intimate receptions at their homes during which they get a chance to mingle with Hillary Clinton.

The Clintons’ steady cultivation of financial benefactors — many of whom had interests before the government — has led to charges of conflicts of interest and impropriety, such as Bill Clinton’s end-of-term presidential pardons sought by donors. Among them was fugitive financier Marc Rich, whose wife, Denise, gave heavily to Democratic causes, including $450,000 for the Clinton Presidential Center in Little Rock.

The Post found that 2,700 loyal supporters — those who have given to both Clintons — have donated more than $129 million for their political races and legal needs. That is a fifth of the $600 million contributed by donors who gave more than $200.

Among them are Elaine and Gerald Schuster, who made his fortune operating nursing homes and public housing developments, tangling with union leaders, government regulators and housing activists in the process. Together, the Boston-based couple have given 53 separate donations to support the Clintons since 1992, including $276,100 for their races and more than $500,000 to their foundation.

“When my father died, the first person I heard from was President Clinton,” said Elaine Schuster. “They have a following of people who would do absolutely anything for them.”

Building such a financial network — and nurturing it over four decades — is not easy, even with the perks of office.

Bill Clinton used his charisma and intellect to captivate new supporters. And Hillary applied her characteristic attentiveness — sending handwritten notes to celebrate engagements and new babies, and poetry books to comfort those in mourning — to win over lifelong allies.

“She remembers everything we ever talked about,” said Susie Tompkins Buell, a close friend and co-founder of Esprit, who, with her husband, Mark, has given $420,000 to the Clintons’ campaigns and $11.25 million to their foundation.

“Hillary does not like to ask for money,” Buell added. “It’s not natural for her. But she’s got really good people who work for her who speak for her, and she’s very, very appreciative when she knows someone has done something for her. And you know it’s sincere.”

As she makes her second White House bid, Hillary Clinton is raising money in a dramatically different environment than her past campaigns. Since then, the Supreme Court has made it easier for wealthy individuals, corporations and unions to spend huge, unregulated sums on political activity.

She has shown a willingness to embrace the new fundraising techniques. This fall, her campaign set up a joint fundraising committee with the Democratic National Committee and 32 state committees that can accept up to $366,000 per year from an individual donor — the first 2016 candidate to pursue such a tactic. And, unlike Sanders, she has sanctioned big-money super PACs working on her behalf, including one coordinating directly with her campaign.

That has given the senator from Vermont an opening.

“I don’t think it’s good enough just to talk the talk on campaign finance reform. You’ve got to walk the walk,” he said to loud applause at a South Carolina forum hosted by MSNBC on Nov. 6, adding, “I am not asking millionaires and billionaires for large campaign contributions.”

Schwerin said that Clinton has fought for stricter campaign finance rules throughout her career and plans to make the issue a major part of her agenda as president.

“In the meantime, however, she will not unilaterally disarm, especially given how Republicans are promising to spend record amounts to tear her down,” he added.

If she secures the Democratic nomination, she is expected to bring in $1 billion during this election cycle — possibly matching what she and her husband collected for all their previous campaigns combined.

To do so, the former secretary of state is leaning on longtime Clinton patrons. Among the 264 individuals or couples who have already raised large sums for her campaign or hosted fundraising events through October are a core of loyal backers who personally contributed at least $73 million to support the Clintons over the years.

But her top fundraisers this year have included two dozen donors who had never before given money to either Clinton, according to The Post’s analysis.

More than two decades ago, one of the nation’s richest executives signed on early to support Bill Clinton’s move to the national stage.

In November 1991, Sam M. Walton, the conservative founder of Wal-Mart, sent an unlikely missive to all his corporate managers: He asked them to donate to Arkansas Gov. Bill Clinton’s presidential bid.

The billionaire retailer was a staunch Republican and fiercely anti-union. The young Democratic governor had entered state politics with the enthusiastic backing of organized labor. But Walton had come to respect Clinton and his wife, who had served on his company’s board for five years.

Walton said he still planned to vote for President George H.W. Bush but would do everything he could to help Clinton secure the Democratic nomination.

“I assure you the Walton family will join many others across the nation to provide Bill maximum financial assistance as well as other campaign support,” Walton wrote in a two-page memo obtained by The Post.

Walton’s relationship with the Clintons illustrated how the young couple won over the state’s business elite, often to the dismay of their union supporters.

Walton first got to know Hillary Clinton in 1983, when her husband tapped her to chair a state educational standards commission. Her panel rolled out a major reform proposal, one that eventually called for required teacher competency testing — an idea abhorrent to the teachers’ unions.

But the initiative was embraced by Arkansas’ corporate leaders, who hoped bolstering the state’s long-flagging school system would spur investment and economic expansion. Walton led an elite group of Arkansas executives — the “Good Suits Club” — who helped the Clintons sell the program.

“It was one of Sam’s first forays into the policy world,” recalled Thomas “Mack” McLarty, a close Clinton friend who was then chief executive of the leading gas utility in the state and one of the dozen business leaders who participated in the effort.

In a little-known episode, the Clintons and their business allies used a then-novel political tactic to build support for the initiative, financing two nonprofit organizations that touted the need for the education overhaul.

The measure was bitterly opposed by teachers’ unions. A leader of the Arkansas Education Association, Peggy Nabors, wrote in a November 1983 letter to teachers around the state that the Clintons’ proposal “had done inestimable damage to the teaching profession,” according to a copy obtained by The Post.

As Hillary Clinton toured Arkansas to promote the reform package, she encountered fierce opposition. “It’s hard. But someday they’ll understand,” her longtime friend Diane Blair recalled her saying, according to a Clinton biography by Carl Bernstein.

The hotly contested measure passed, and the initiative, which included more money for public schools, eventually yielded improvements in Arkansas’ educational system.

Just as Hillary Clinton predicted, the teachers’ unions came around.

Although other Arkansas labor leaders remained deeply disappointed by the Clinton record, Nabors had become an avid supporter by the time Bill Clinton ran for president in 1992, joining the campaign to tout his education record.

“We disagreed strongly on that one issue but were in agreement on so many others,” she said in an interview. Nabors said she told the Clintons, “Everyone has the opportunity to be wrong at least once, and this was yours.”

Today, the two major national teachers’ unions rank among the Clintons’ biggest supporters. The National Education Association has contributed at least $1.3 million to bolster their races, while the American Federation of Teachers has given more than $756,000 to support them politically and at least $1 million to their foundation.

In July, AFT endorsed Hillary Clinton’s 2016 presidential bid — the first national union to do so.

The Clintons’ Arkansas experience would prove to be a template for their national approach. Time and again, they sided with business interests, infuriating their liberal allies. But the estrangement was rarely permanent.

“They made a very conscious move toward the center, in part probably because of fundraising demands and in part because of ideology,” said Andrew Stern, former president of the Service Employees International Union. “They believe — as I do — that the Democratic Party has to be pro-growth.”

By the time the Clintons left Arkansas, they had forged strong relationships with the state’s power structure. Hillary Clinton was a corporate lawyer at the Rose Law Firm, the embodiment of the Little Rock establishment. She had become good friends with James B. Blair, an early donor to Bill Clinton and counsel to Tyson Foods, who encouraged her to join him in investing in commodity futures, where she parlayed a $1,000 initial investment into a $100,000 profit. And she had served on several company boards, including Wal-Mart, which gave her more than $100,000 in stock options.

Walton and his wife, Helen, who both wrote $1,000 checks to Bill Clinton in 1991, did not donate to Clinton campaigns after that race. But their daughter, Alice Walton, has remained an ally, contributing $25,000 to Ready for Hillary, a super PAC that laid the groundwork for her 2016 bid. And Wal-Mart itself has been a big supporter of the Clinton Foundation, donating close to $1.2 million to finance student-run charitable projects and paying $370,000 in membership fees since 2008, according to a company spokesman.

Other key alliances took root in Arkansas. It was in Little Rock that Bill Clinton met Charlie Trie, the owner of a small restaurant who would later plead guilty to a scheme to funnel illegal donations originating in China into Democratic Party coffers. Clinton’s friendships with Arkansans such as producer Harry Thomason and actor Mary Steenburgen helped open doors in Hollywood, a key source of money for later campaigns. And his connections to the state’s banking families would later help him deftly navigate Wall Street.

As a young Democratic finance staffer, Matt Gorman was one of the first to get a look at the national fundraising network that then-Gov. Bill Clinton had started building from his base in Arkansas. It was a box crammed with business cards, Georgetown University alumni newsletters and cocktail napkins scrawled with notes such as, “Call me if you ever run for president.”

“I never saw anything like it,” said Gorman, who was handed the box when he arrived in Little Rock in August 1991.

Gorman sorted the motley collection into 50 manila envelopes — one for each state other than Arkansas, as well as Puerto Rico — and began appealing to skeptical party financiers to back the little-known governor in his bid for the White House.

From those humble origins, the Clintons constructed an unsurpassed fundraising operation that soon reached into every major industry — from venerable Wall Street institutions to emerging powers in Silicon Valley.

It began with the sheer force of Bill Clinton, up close.

Ken Brody, a Goldman Sachs executive who had gotten to know the young governor through the centrist Democratic Leadership Council, brought Clinton to a small dinner party in Manhattan in 1991. There, he bowled over the group of 15 influential bankers and media executives, including then-Goldman Sachs co-chairman Robert Rubin.

“It was a remarkable evening,” Rubin recounted in an oral history he gave for the William J. Clinton Presidential History Project. “It was about three hours or thereabouts, and he engaged with people in a way that nobody else I had seen in political life had, that sort of give and take. I left there thinking to myself, ‘This is a very impressive guy.’ ”

Rubin joined Clinton’s campaign as an economic adviser, and other Goldman Sachs partners mobilized their networks to raise money for the upstart candidate.

Across the country, Clinton had a similar impact on the conservative businessmen who then ran Silicon Valley.

At a brunch organized by Democratic fundraiser Gloria Rose Ott at the newly opened Fairmont Hotel in San Jose, the Arkansas governor dazzled the guests, including Apple chief executive John Sculley and Hewlett-Packard president John Young, both longtime Republicans.

“He had a stunning conversance about what we were doing here and why people should be paying attention to Silicon Valley,” said former California state controller Steve Westly, an early executive at eBay.

Sculley and Young helped draft the campaign’s high-tech policy. And in September 1992, they were among more than 20 top industry leaders — many of them lifelong GOP backers — who held a news conference endorsing Clinton.

That night, venture capitalist Sanford Robertson hosted a $5,000-a-couple fundraiser for Clinton at his historic San Francisco mansion with other industry leaders, helping raise more than $300,000 for the campaign.

Once in office, Clinton brought many of his new friends from Wall Street and the tech sector to Washington. Sculley had a seat next to Hillary Clinton at her husband’s first State of the Union address. Ott was appointed to the Overseas Private Investment Corporation. Brody was named the head of the Export-Import Bank. And Rubin was tapped to lead the National Economic Council, eventually becoming treasury secretary.

Like-minded Wall Streeters such as investment banker Roger Altman joined him in the new administration, and early on they helped craft an economic policy — known as Rubinomics — that was applauded by Wall Street but viewed critically by many on the left.

When then-first lady Hillary Clinton decided to run for the Senate in New York in 2000, she turned to Rubin and Altman to introduce her to key players on Wall Street.

Wall Street’s influence prevailed during most of Bill Clinton’s presidency but ran into an unexpected hurdle late in his second term — thanks in part to his wife. At the time, big banks and allied businesses had formed a powerful lobbying coalition seeking more clout in recovering assets in the growing number of personal bankruptcies.

Labor leaders and Harvard Law School professor Elizabeth Warren led opposition to the bill, arguing it would hurt debt-burdened families while enriching the banking sector. For help, Warren turned to the first lady, who came to her Harvard Law School office in 1998 and discussed the measure at length.

After the meeting, Hillary Clinton vowed to fight against “that awful bill,” Warren wrote in her book, “A Fighting Chance.”

Hillary Clinton joined with Sen. Edward M. Kennedy (D-Mass.), writing letters and calling members of Congress to oppose the bank-sponsored legislation. But after a costly, intense lobbying campaign — during which President Clinton stayed silent — the bill passed Congress in 2000.

Then, in the waning days of his administration, the president disappointed the bankers and left the bill unsigned, effectively vetoing it. He did so after having been “urged on by his wife,” Warren wrote.

A year later, however, Hillary Clinton played a decidedly different role when she was faced with a similar bankruptcy bill as a freshman senator. She had just been elected with the strong support of the financial sector, which contributed $2.1 million of the $30 million she raised in 2000, one of the largest industries to back her, The Post’s analysis found.

The measure her husband had vetoed was reintroduced in Congress, and Clinton switched sides — supporting it, along with 36 other Democrats.

She argued that the legislation had been improved since her earlier opposition. At her insistence, she said, sections were removed that would have ended special protection for child support payments. Even so, the bill — which failed — was vigorously opposed by consumer groups and unions that said it would harm the poor and vulnerable while giving huge advantages to banks, credit card companies and car dealers.

Warren, who declined to comment for this article, later recalled Clinton’s switch with some bitterness.

“The bill was essentially the same, but Hillary Rodham Clinton was not,” Warren wrote in her 2003 book, “The Two-Income Trap,” published nine years before she was elected to the Senate. “Big banks were now part of Senator Clinton’s constituency,” she added.

Clinton has since said she regrets her 2001 stance and opposed a similar bankruptcy bill when it was passed in 2005. (She missed the vote because her husband was in surgery.)

Over her political career, she has maintained close relations with the financial sector, which tops the list of industries that have supported her, according to The Post’s analysis. Other major sectors that have backed her include the entertainment industry, health care and real estate.

Since 2000, Hillary Clinton has raised $29.2 million from the PACs and employees of banks, hedge funds, securities firms and insurance companies, according to The Post analysis. During his political career, Bill Clinton raised $39.7 million from the same sector.

In her current campaign, Clinton has pledged to rein in Wall Street. She has proposed higher taxes on high-frequency traders and an end to special tax breaks for hedge fund managers, and recently called for more aggressive enforcement of criminal statutes that govern the finance industry.

But her rhetoric has not alarmed her backers in the financial sector. So far, donors in the banking and insurance industries have given $6.4 million to her campaign and allied super PACs, behind only those in communications and technology, The Post found.

Hillary Clinton is drawing enthusiastic support from Silicon Valley, one of the first industries to rally around her husband nearly a quarter-century ago.

Marc Benioff, chief executive of the cloud computing company Salesforce.com, gave $50,000 with his wife, Lynne, to the Ready for Hillary super PAC in 2013. The next year, Salesforce.com paid Hillary Clinton $451,000 to deliver two speeches.

Eric Schmidt, executive chairman of Alphabet, the parent company of Google, and one of the biggest players in the industry, has said he’s a fan of Clinton. And her campaign has hired a new start-up Schmidt helped bankroll called the Groundwork, which is developing cutting-edge technology to help engage supporters.

Other top tech executives and entrepreneurs are jockeying to host events for her campaign. Among them: Michael and Xochi Birch, founders of the social networking company Bebo, who crammed 145 people into their San Francisco mansion in September for a breakfast reception with the candidate.

“Hillary shows up with this great lineage and this incredible Rolodex she’s cultivated over the years,” Westly said. “She has built a very, very strong base.”

The power of Hillary Clinton’s donor base — and its steady expansion — was encapsulated by a 14-event cross-country fundraising sprint she did in late September, bringing in at least $4.4 million for her campaign in just six days.

Clinton started in New York, where John Zaccarro Jr., a real estate developer and son of the late Geraldine Ferraro, hosted 135 donors at his home. Zach Iscol, whose mother, Jill, is a close friend of Hillary Clinton, had another 100 contributors at his residence two days later.

In New Jersey, Clinton headlined a fundraiser at the estate of public-relations executive Michael Kempner. Among the guests was New Jersey Senate Majority Leader Loretta Weinberg, who told the crowd about how she met the then-first lady two decades earlier to discuss legislation that would guarantee that new mothers could have an overnight hospital stay.

A few days later, she was in California, mingling with Saban and other old Hollywood friends at the Brentwood home of studio chief Rob Friedman and his wife, Shari.

But she wasn’t just feted by longtime family loyalists. The network now has new players such as Tracey Turner, a microfinance entrepreneur who held an event for Clinton at her home in Belvedere, Calif.

“This is the first time I’ve done anything remotely like this,” Turner said. “I have a daughter who is 6, and I thought, ‘You know what, I want my daughter to be part of this moment in history.’ ”

She pitched the campaign on an unusual idea — a “bring your child to meet the first woman president” fundraiser.

And that’s how 150 supporters and just as many kids gathered in Turner’s yard on a Monday afternoon for a garden party that raised at least $400,000 for the campaign. Clinton ditched her stump speech and instead fielded questions from the kids.

“Everyone went wild,” recalled Turner, who said the former secretary of state fielded topics that ranged from the height of the Washington Monument to the plight of Syrian children.

Later that evening, Clinton collected at least $310,000 more at the home of trial attorney Robert Shwarts and photographer-writer Joni Binder in Orinda, Calif. The couple have done little political fundraising, hosting just one previous reception for Clinton in 2007.

But they were eager to take part again this year.

“It’s intimate — she’s funny and she makes eye contact, and you feel like she’s talking just to you,” Binder said. “When everyone walked out, no one’s feet were touching the ground. You left hugging total strangers.”

Binder is now all in with the Clintons — for the long haul.

“I’m at their beck and call,” she said. “I would do anything that they asked.”

Originally published by The Washington Post