Top House and Senate progressives are demanding a meeting with President Obama to underscore their opposition to cuts in Social Security benefits as part of a budgetary grand bargain — a sign that the left has no intention of allowing cuts without a major fight.

The demand is in a letter signed by Congressional Progressive Caucus cochairs Keith Ellison of Minnesota and Raul Grijalva of Arizona, along with Democratic Reps. Jan Schakowsky, John Conyers and Donna Edwards and Sen. Bernie Sanders, an independent.

“We appreciate your ongoing efforts to negotiate with Congressional Republicans in a serious, thoughtful manner, despite their unwillingness to consider a balanced approach,” it says. “However, at a time when many Americans are struggling, cutting Social Security benefits would take money directly out of the pockets of American seniors and slow our economic recovery.”

More than 100 House Democrats have already signed a letter opposing “chained CPI,” a way of indexing benefits payments to inflation that would amount to a cut in benefits.

The backdrop for all this is that top Democrats are seriously discussing temporarily “turning off” the so-called sequester, thanks to the outcry over sequestration-caused flight delays. With Republicans complaining about the delays — and blaming Obama for them even as they claim the sequester as a victory for themselves — Senate Majority Leader Harry Reid has called the GOP’s bluff by suggesting the counting of war savings to replace the sequester cuts.

The White House endorsed Reid’s idea last week, claiming that the sequester could be suspended while a “balanced” replacement is sought.

Liberals and unions have long pushed for outright cancellation of the sequester. Progressives hope that their stiff opposition to cuts in entitlement benefits will convince Obama and Democratic leaders that suspending the sequester is a better outcome than any “grand bargain” that alienates the left. Republicans are all but certain to oppose that approach.