Is John McCain's Candidacy Over?

So there may soon be two new entrants into the Republican Presidential field for 2008. One is a John McCain wanna-be, who is nowhere near as popular as McCain among the rank-and-file. (And yes, that means he's awfully unpopular). Put him down as either an also-ran, or an independent candidacy. In that latter capacity, he might well hurt the Democrats more than the Republicans, by splitting the anti-Iraq war vote.

The other is a good friend of John McCain, who apparently stayed out of the race at least in part out of deference to him. If he steps in, he will instantly become the strongest conservative - and he may wind up sucking up all the oxygen that Mitt Romney is currently using, and leaving it a two-man race with Rudy Giuliani. Thompson would be a very serious contender.

But are these signs that McCain's candidacy is no longer seen as viable, or is it a signal (from friends) that he should get out?