A dire warning from Defense Secretary Leon Panetta about the consequences for the military if the super committee fails could come back to haunt the White House — and Congressional Democrats.

A Monday letter from Panetta to GOP Sens. John McCain (Ariz.) and Lindsey Graham (S.C.) outlined a litany of cuts he contended would be necessary if $600 billion in automatic cuts to defense spending is triggered by the Joint Committee on Deficit Reduction’s inability to find an alternative way to shave $1.2 trillion from the deficit.

Panetta called the potential cuts “devastating” and warned that they could result in “the smallest ground force since 1940, the smallest number of ships since 1915, and the smallest Air Force in its history.”

While his warning might help spur the super committee to reach a deal and provide cover for lawmakers to vote for one, a failure by the panel could put his boss — President Barack Obama — and Congressional Democrats in a tough spot.

“I hope it focuses everybody’s attention, yeah, on both sides,” super committee member Sen. Rob Portman (R-Ohio) said.

If the committee fails, the letter will be waved like a bloody shirt by Republicans looking to block the cuts regardless of the consequences to the deficit.

Graham predicted Tuesday that Obama and Democrats would not be able to credibly block efforts to remove the trigger given the dire consequences Panetta predicted.

“I hope the president will look at Leon’s letter,” Graham said. “It was a devastating analysis of what would happen to this country if we pulled this sequester trigger. … There is a definite disconnect there. … I hope the president, I hope he’d read the letter and say, ‘You’re right, this is a bad idea’. … This was the most ill-conceived idea I can imagine.”

Graham said he hopes the super committee gets a result for the good of the country, but that if it doesn’t, the trigger should be replaced with something that doesn’t cut defense.

McCain, meanwhile, thanked Panetta.

“Your letter, I hope, is read by every Member of Congress and every citizen of this country because we cannot put our nation’s national security at risk,” McCain said at an Armed Services hearing Tuesday at which Panetta testified.

Democratic leaders and the White House, however, have so far talked tough about maintaining the trigger, with Obama himself warning the super committee co-chairmen in phone calls Friday that he would not accept efforts to partially roll it back.

“If the committee fails to act, sequestration is going to go forward,” Senate Majority Leader Harry Reid (D-Nev.) warned Tuesday. “Democrats are not going to take an unfair, unrealistic load directed toward … domestic discretionary spending and take it away from the military.

“The president says that if it comes about during the next year, he’ll veto it. … Those who are — who talk about retracting the sequester are wrong and are not living up to the agreement we reached to cut our nation’s deficit last July,” Reid added.

Senior Democratic aides predicted Tuesday that their caucus would be able to block efforts to roll back the defense cuts without a negotiated debt deal. They noted the potential hit on the nation’s credit rating, which has already been downgraded a notch by Standard & Poor’s rating agency, if the trigger is diluted without cutting the deficit somewhere else.

“If you try to mess with the trigger, you are really risking the U.S. credit outlook,” one senior aide said.

And aides said Democrats would be able to credibly make the case that the reason these big defense cuts are looming is because Republicans weren’t willing to increase taxes on the wealthy.

“They own the fallout,” one aide said.

Democrats said they aren’t going to just hand over their leverage for free and will continue to push Republicans to negotiate a deal even if the committee fails, aides said.

Given that there is a whole year before the cuts take place, Congress could have plenty of time to craft a new deal.

The aides also dismissed Panetta’s warnings as typical talk from any Defense secretary. “He’s an advocate for his department, and that’s understood,” one said. “The president takes a more holistic view. … He isn’t going to be bullied.”

But Republican aides said the pressure would be on Democrats to agree to spending cuts somewhere else, given that Obama’s own Cabinet secretary warned the sequester could risk national security.

Senate Armed Services Chairman Carl Levin (D-Mich.) continues to refuse to discuss the possibility of the super committee failing.

“Once you speculate on it, you take away some of the power of the threat of sequestration,” Levin said.