Rep. Jeb Hensarling (R-Texas), center, joined by Rep. Xavier Becerra (D-Calif.) left, and Sen. Rob Portman( R-Ohio), right, arrive for the start of the opening meeting of the Joint Select Committee on Deficit Reduction or "supercommittee.” (J. Scott Applewhite/AP)

But right now, there has never been less fear of the trigger. Even Rep. Jeb Hensarling, the Republican co-chair of the supercommittee, is talking about modifying it in the event the supercommittee can’t come to an agreement. By doing that, he’s making it less likely that the supercommittee does come to an agreement, which might say something about how much Republicans actually want this process to succeed.

Hensarling’s office did not respond to a request for comment, but other offices involved in this process did. And they made a fair point: The trigger might be harder to defuse than people think. In fact, it might be almost as hard as coming to a deal in the first place.

The trigger is law. It is part of the Budget Control Act of 2011, which passed in August. To change the law, the two parties would need to agree on how to change it. So it’s not enough for Republicans to say they would like to see the trigger “reconfigured.” It’s not even enough for Democrats to also want to see the trigger reconfigured. The two parties have to agree on how to reconfigure it. And that would be difficult for the same reason that passing a deficit-reduction deal is difficult.

The two parties would like, in the abstract, to reduce the deficit, but have trouble agreeing on the specifics of how exactly to get there. The result is inaction. Similarly, the two parties would probably like, in the abstract, to defuse the trigger, but arguments over how best to do that could again lead to inaction. And inaction means the trigger goes off.

Republicans want to lift the defense cuts. Some Democrats do, too. But Democrats don’t want to lift the defense cuts without lifting the cuts to domestic programs. And Republicans don’t want to do that. Nor do Republicans want to replace the defense cuts with tax increases. So it’s not clear what they can offer the Democrats that they’ll actually want.

Another option would be to defuse the trigger altogether, but that could get the ratings agencies involved again, and so there is likely to be substantial opposition from many members of Congress, and potentially from the White House. “I would not vote to undo the sequester,” Senate Majority Leader Harry Reid said Tuesday.

So could Congress defuse the trigger? Sure. The supercommittee is law, and the law is whatever Congress says it is, within the limits of the Constitution. But to defuse the trigger, Congress will need to agree on a $1.2 trillion deficit-reduction plan they like better. And if they could do that, we wouldn’t be talking about the trigger in the first place.