He has zero chance of getting any Dem Prez nomination.
His only chance of surviving 2012 is having the liberals at the WashPost cover his butt and make him out to be mr conservative. This is all about 2012 re-election.
That said, I don't think he would win if he tried to get the nomination in for prez, but he would have an impact, which might be all he wants (or the VP slot from Biden).
He has an ego, he's unhappy, and he's on the irrelevant side now, that might be all the motivation the man needs to make an ass of himself.