Nate Silver gives odds:
Economic performance has been poor enough, and economic forecasts have been downgraded enough, that I’d consider Mr. Obama to be in a rough toss-up against a strong and relatively moderate nominee like Mr. Romney. Meanwhile, I’d consider him to be a clear favorite against someone like Ms. Palin or Ms. Bachmann. And he’d be a slight favorite against a candidate like Mr. Pawlenty.
Chait doubts that Romney will win the nomination.
The Dish 