Right now, the only thing that stands between McCain and the nomination is Florida and Rudy Giuliani.
No, if Thompson drops out, McCain has to keep Fred's evangelical vote from going to Huckabee. He certainly needs to wath Romney, who has after all, won three states to McCain's two. And most importantly, McCain needs money.
McCain's in better shape than he was pre-NH, but it is certainly not as simple as knocking off the guy coming in 6th in most contests.
Money won't be an issue if McCain wins Florida. Momentum, right there, for once, is more important than money.