The failure of the Congressional Progressive Caucus to stand up to President Obama on many vital matters of principle is one of the most important – and least mentioned – political dynamics of this era.

As the largest caucus of Democrats on Capitol Hill, the Progressive Caucus has heavyweight size but flyweight punch.

During the last four years, its decisive footwork has been so submissive to the White House that you can almost hear the laughter from the West Wing when the Progressive Caucus vows to stand firm.

A sad pattern of folding in the final round has continued. When historic votes come to the House floor, party functionaries are able to whip the Progressive Caucus into compliance. The endgame ends with the vast majority of the caucus members doing what Obama wants.

That’s what happened on the first day of this year, when the “bipartisan” fiscal deal came down. Widely denounced by progressive analysts, the bill passed on the House floor by a margin of 44 votes – with the Progressive Caucus providing the margin. Out of 75 caucus members, only seven voted against it.

Over the years, we’ve seen that President Obama is willing – even satisfied – to be rolled by Republican leaders on Capitol Hill. But that’s just part of the problem. We should also come to terms with the reality that the Progressive Caucus is routinely rolled by the president.

A two-step prototype hit the ground running in September 2009 when Progressive Caucus co-chairs sent a public letter to Obama on behalf of the caucus – pledging to vote against any healthcare bill “without a robust public option.” Six months later, on the House floor, every member of the Progressive Caucus wilted under pressure and voted for a healthcare bill with no public option at all.

Since then, similar dynamics have persisted, with many Progressive Caucus members making fine statements of vigorous resolve – only to succumb on the House floor under intense pressure from the Obama administration.

We need Progressive Caucus members who are progressives first and loyal Democrats second, not the other way around. When the party hierarchy cracks the whip, they should strive to halt the rightward drift of congressional legislation, not add to it.

In the new session of Congress, the Progressive Caucus – with 72 members – retains major potential. It often puts out solid position papers like the recent Budget for All. And its leadership includes some of the sharpest progressive blades in the House. Congressmen Keith Ellison and Raul Grijalva just won re-election as caucus co-chairs, and Congresswoman Barbara Lee just became the caucus whip.

Still, none of the more than half-dozen Progressive Caucus leaders were among the seven caucus members who voted against the New Year’s Day fiscal deal – and more serious capitulation may soon be on the near horizon.

Early this month, right after the fiscal deal, the Progressive Caucus put its best foot forward by issuing a “Progressive Principles for the Next Deal” statement that vowed to “protect” Medicare, Medicaid and Social Security benefits. But those programs will be in jeopardy before spring in tandem with votes on “sequestration” and raising the debt ceiling.

The results are likely to be very grim unless members of the Progressive Caucus are truly prepared – this time – to stand their progressive ground. Without an attitude adjustment, they’re on track to help the president betray Social Security and other essential parts of the social compact.

On a vast array of profound issues – ranging from climate change and civil liberties to drone strikes, perpetual war and a huge military budget – some individual progressives in Congress introduce outstanding bills and make excellent statements. But when the chips are down and minority leader Nancy Pelosi offloads presidential weight onto House Democrats, the Progressive Caucus rarely shows backbone with cohesive action.

What we have witnessed so far is surrender in stages – a chronic confluence of conformity and undue party loyalty, with brave talk from caucus members habitually followed by contrary votes on the floor of the House of Representatives. From the grassroots, progressives must mobilize to pressure every member of the Congressional Progressive Caucus to let them know we will hold them accountable.

Norman Solomon is co-founder of RootsAction and founding director of the Institute for Public Accuracy. He co-chairs the Healthcare Not Warfare campaign organized by Progressive Democrats of America. His books include “War Made Easy: How Presidents and Pundits Keep Spinning Us to Death.” He writes the Political Culture 2013 column.