What, then, of the possibility that congress will just agree to get rid of the cuts and let the deficit go up, either openly or through the use of budget gimmicks? On the surface, this seems the most likely scenario, since it’s probably the case that relatively few members from either party actually care very much about the size of the deficit. But it’s here that the congressional math quickly gets tricky: While there are plenty of Democrats who support high levels of Pentagon spending, there are also plenty who would jump at the chance to cut it. Likewise, while there are plenty of Republicans who don’t mind looking the other way on the deficit if it achieves other goals, there are quite a few Tea Partiers who would be very reluctant to vote that way. As a result, a vote to defuse the defense cuts trigger at the expense of the deficit would most likely pit centrist Republicans and Democrats against the more ideologically extreme wings of their parties, and there’s no guarantee which coalition would win. Remember, too, as we head into another election cycle, that Republicans are still awfully afraid of Tea Party primary challenges and of charges that they’ve gone Washington; for a lot of them, avoiding those problems may overshadow everything else.

As for hiding the deficit behind budgeting gimmicks, the same problem applies—and in fact maybe even more so. Indeed, the Tea Party has long railed against what they believe to be the deceptive bookkeeping of politicians on both sides of the aisle in Washington. And for purists like the Tea Party, procedures can matter. A lot. Tea Party activists might therefore be even more upset about increasing the deficit through clever budgeting tactics than it would by congress openly increasing the deficit to save the Pentagon.

Of course, this doesn’t mean there’s no chance for congress to avoid the trigger and its significant cuts in defense spending. First of all, the votes could fall the other way, with the middle able to defeat the extremes. Second, I suppose it’s also possible that Democrats could end up caving after all. And the third, most likely scenario is that the 2012 elections could upend the balance of power and the chances of both sides reaching a deal or one side being able to enact its preferences may change. After all, even if sequestration does take place in January 2013, Congress can always reverse it soon after. But until that point, my guess is that the trigger is going to prove to be a tough obstacle indeed.

Jonathan Bernstein blogs at A Plain Blog About Politics.