All bargaining is not alike; different negotiations call for different strategies. During the debt limit debate, the default -- if nothing at all passed -- would have been a total disaster for Barack Obama and the Democrats. On both Obama's jobs bill and his new deficit reduction plan, the default -- if nothing at all passes -- is not a total disaster for Barack Obama and the Democrats. That is almost certainly what's driving what everyone perceives as a more aggressive strategy from the White House.
I said this yesterday over at Greg's place, but I don't think I wrote it very well, because Doug Mataconis read it as a claim that Obama can use his leverage here to win his jobs bill. That's not what I meant to say, particularly; it's not that I think Obama necessarily has a lot of leverage to get what he wants, but that House Republicans have much less. In other words, not that Obama should "win" this one, but that it was inevitable that he was going to "lose" the last one -- the only question was how, what, and by how much. Obama could have been as aggressive as he wanted to be over the debt limit, but eventually he needed to cut a deal with Republicans -- and most Republicans didn't feel that they needed to cut a deal with him, and they had a significant electoral incentive to feel that way. This time around, when it comes to the Joint Select Committee, there's no obvious electoral reason for either side to care whether the trigger is invoked, regardless of the substantive concerns they may have (which, as I see it, are pretty much a push anyway).
In keeping with what I was saying earlier about people not knowing their own motivations...Ezra Klein had a reported piece about how the new WH aggressive posture on the deficit is a deliberate strategy, derived from what they have learned over the course of the year and in particular from the debt limit negotiations. And I'm sure that he has it right: this is, let's say, exactly how White House staff see it. They've learned something, and they've changed their strategy accordingly. But that doesn't necessarily mean that their self-description of the causal chain here is accurate. It's perfectly possible -- and in my view, likely -- that what's really happening is that given that the bargaining context has changed, what makes sense to them has changed, and that they see that as "learning" when it's actually just holding a different hand.