The Obama administration spent nearly $18 billion on immigration enforcement last year, significantly more than its spending on all the other major federal law enforcement agencies combined, according to a report published Monday by the Migration Policy Institute, a nonpartisan research group in Washington.

Based on the vast resources devoted to monitoring foreigners coming into the country and to detaining and deporting illegal immigrants, immigration control has become “the federal government’s highest criminal law enforcement priority,” the report concluded.

In recent years, it found, the two main immigration enforcement agencies under the Department of Homeland Security have referred more cases to the courts for prosecution than all of the Justice Department’s law enforcement agencies combined, including the F.B.I., the Drug Enforcement Administration and the Bureau of Alcohol, Tobacco, Firearms and Explosives. Total spending on those agencies was $14 billion, official figures show.

The 182-page report was an opening salvo in a contentious debate over immigration that President Obama has pledged to lead this year. Its purpose was to marshal publicly available official figures to show that the country has built “a formidable enforcement machinery” since 1986, the last time Congress considered an overhaul of the immigration laws that included measures granting legal status to large numbers of illegal immigrants. Spending on immigration enforcement was 15 times greater last year than in 1986, the report found.

The report responds to lawmakers, mainly Republicans, who have argued that federal authorities must do much more to strengthen enforcement before Congress can consider any legalization for an estimated 11 million illegal immigrants in the country.

“The ‘enforcement first’ policy that has been advocated by many in Congress and the public as a precondition for considering broader immigration reform has de facto become the nation’s singular immigration policy,” the report concluded.

Although the institute includes both Democrats and Republicans and did not offer any recommendations in this report, it has previously supported policies to bring illegal immigrants into the legal system, rather than expelling them.

According to the report, financing, staffing and technology investments for the Border Patrol have reached “historic highs,” while apprehensions of illegal border crossers have plunged by 53 percent since 2008. As a result of huge increases in spending, deportations have also “increased dramatically,” the report says, with far more immigrants removed in expedited proceedings that do not involve any formal proceeding before an immigration judge.

The budget for Immigration and Customs Enforcement, which handles interior enforcement and detention, has increased by 87 percent since 2005, to nearly $6 billion, according to the report. The number of foreigners the agency detains annually increased to 429,247 in 2011. In December, the agency announced it had deported 410,000 foreigners in 2012, giving Mr. Obama the record for the highest number of removals during his term.

“As a result of 25 years of investment,” said Doris Meissner, an author of the report who is a senior fellow at the institute, “the bulwark is fundamentally in place.” She said the existing system made it unlikely that an immigration overhaul could unleash a new wave of illegal migration, like the surge since the amnesty of 1986.

Ms. Meissner, who served as commissioner of the immigration service in the Clinton administration, said public perceptions of uncontrolled migration across the border with Mexico “have not caught up with the reality.”

Since the Sept. 11 terrorist attacks, federal law enforcement agencies have revamped and coordinated databases for monitoring the movement of foreigners into the country. An immigration databank that federal authorities have created is the “largest law enforcement electronic verification system in the world,” said Donald Kerwin, another author of the report.

Some critics said the report’s figures were misleading because they include the entire budget for Customs and Border Protection, another Department of Homeland Security agency, which also oversees cargo inspections on land and at seaports.

“A large amount of that spending has nothing to do with immigrants,” said Mark Krikorian, the executive director of the Center for Immigration Studies, a research organization that supports tough measures against illegal immigration. Immigration enforcement still has “gaping holes,” he said.

One of them, Mr. Krikorian said, is the lack of a national system for employers to verify that new hires are legally authorized to work. He also noted that the United States still has no system to confirm that foreigners leave the country when their visas expire.

Other experts said the report was an accurate summary of a recent transformation in immigration control. “There is no question that there has been a big, big increase in enforcement across the board,” said Edward Alden, a senior fellow at the Council on Foreign Relations.