When Raul Grijalva and Lynn Woolsey told the co-chairs of the Cat Food Commission that they would 100% oppose Social Security cuts, it was pitched as the opening salvo in an aggressive pushback against any changes to benefits. There would be plenty of “CPC-wide follow up” in September, particularly when Congress returned to session, I was assured.

Well, that has begun. Grijalva, John Conyers (D-MI) and Dan Maffei (D-NY) are spearheading an effort, with a “Dear Colleague” letter, to sign on to a statement of principles regarding the deficit commission: “If any of the Commission’s recommendations cut or diminish Social Security in any way, we will stand firmly against them.” Here’s part of the Dear Colleague letter:

Social Security belongs to the workers and their families who have worked hard, paid taxes in, and earned its benefits– it is a promise that must not be broken. Social Security is not the reason for the deficit and it should be protected for today’s and tomorrow’s beneficiaries.

Stand with us in support of Social Security, a promise made to Americans of all generations. Join us in calling on President Obama to protect Social Security in its entirety.

This was first reported by Brian Beutler at TPM, and already Mary Jo Kilroy (D-OH), Chellie Pingree (D-ME), and co-chair of the Progressive Caucus Lynn Woolsey (D-CA) are on board, with dozens more expected. In addition, Sen. Bernie Sanders, a member of the Progressive Caucus, penned an op-ed today strongly opposed to benefit cuts.

An aide to Rep. Conyers believes this effort will be the “key organizing tool on this issue,” and identifies numerous progressive groups who have agreed to help push it, including many of the same groups involved in the Hands Off Social Security effort. They will whip the vote not only internally in the Progressive Caucus but throughout the Democratic caucus.

But there’s more. The ringleaders of this effort may try to move this to the floor in the form of a privileged resolution in September, forcing an up-or-down vote in the House. While some involved with the effort believe that the letter serves the same purpose as a privileged resolution, which would have to get a vote according to the rules of the House, Rep. Grijalva’s spokesman confirmed, “we’ve definitely thought about that avenue.” They want to see what kind of traction they get on the letter in the next couple weeks before committing to additional steps.

But a resolution would be a major raising of the stakes. As I’ve been documenting, Democrats have walked themselves into a box canyon by putting Social Security out front in the election campaign, and casting Republicans as the villains. By putting the question of benefit cuts up to a formal House vote, they can cement that dynamic by forcing Republicans to vote, essentially, for benefit cuts. But Democrats would have to make a choice that could affect their futures, as well, and right before an election. So clearly, a privileged resolution would be the “nuclear option” of this debate. It would be near-impossible for Democrats to vote against it in large numbers. And the deficit commission would have a hard copy of 230 or so votes against their preferred option.

As I said, it may not come to that. But it’s definitely being discussed. And, the whole purpose of the letter is to “get people on the record before the election,” as the Conyers aide told me. This could be a moment where the plans of Democrats electorally runs headlong into plans for policy.

The letter is on the flip.

Dear Mr. President,

We write today to express our strong support for Social Security and our view that it should be strengthened. We oppose any cuts to Social Security benefits, including raising the retirement age. We also oppose any effort to privatize Social Security, in whole or in part.

You have charged the National Commission on Fiscal Responsibility and Reform with proposing recommendations that improve the long-term fiscal outlook and address the growth of entitlement spending. It is our view that Social Security–which is prohibited by law from adding to the national budget deficit–does not belong as part of those recommendations.

By 2023, Social Security will have built up a $4.3 trillion surplus, and, without any action, can pay at least 75 percent of all benefits thereafter. Because Social Security is funded separately from the general treasury and has no borrowing authority, it has not contributed to the federal deficit. Despite these facts, some Commission members have repeatedly alleged the need to cut Social Security for budgetary reasons.

For 75 years, Social Security has been a promise to the American people that if they work hard and pay their fair share, they will have a financially secure retirement. In communities across this country, Social Security benefits are often the only source of income helping families maintain a decent standard of living. Social Security’s benefits are modest, averaging less than $13,000 a year, but they are vital to the vast majority of Americans who receive them.

Cutting Social Security benefits further than they are already being cut by raising the retirement age from 65 to 67 would create needless hardship for millions of vulnerable Americans. This is especially true in the face of an economic downturn that has wiped out trillions of dollars that Americans were relying on for their retirement security and the increased dismantlement of the private and public pension systems.

If any of the Commission’s recommendations cut or diminish Social Security in any way, we will stand firmly against them. We urge you to join us in protecting and strengthening Social Security rather than letting it fall victim to a misguided attempt to reduce budget deficits on the backs of working families.