Latest polls actually show Giuliani with a double-digit lead on McCain from evangelicals. Interesting thing is that Giuliani is a pro-choice pro-glbt rights candidate, while McCain has been courting the hell out of the religious reich for most of his career. McCain is a political chameleon and a right bastard--the Republican equivalent of Hillary. He's also got about as much charisma as a wet sock. But he's a media darling, which might help him. Thing is, I don't think he can get the independent vote anymore, since he's been drifting so hard right lately. And without the independents, and without the evangelicals, he hasn't got a prayer.
Giuliani, on the other hand, is a real problem. He'll take the independent vote and probably a few Dem votes as well. He's the mayor that saved New York from 9/11, remember. Whoever goes against Giuliani will have to either play to the right or label Giuliani as a conservative somehow in order to retain any chance at claiming the middle ground. Hillary can't beat Giuliani, because Hillary is a terrible candidate. Barak Obama? As far as I'm concerned, he's an empty suit. He hasn't put forth any ideas or anything substantive from his campaign - he's just a charisma machine. Which might work for him, but if Giuliani tacks to the right and captures the South, and the rest of the Repub vote, and captures the independents, Obama's finished.
Of the Democratic candidates, I believe the person with the best chance against either Giuliani or McPain is John Edwards. He's a charismatic southerner who can capture the core Democratic constituencies, labor and black voters, and he's got enough solid policy ideas churning out of his campaign that he might be able to capture the middle as well. And if he can get enough crossover Republican support against Giuliani in the south, he might be able to pull it off.
The bottom line is that the real threat is Giuliani, not McShame.