McCain has opposed his party much more than Clinton has opposed hers. And he’s got the enemies to prove it. I won’t totally knock Clinton, she’s made some enemies on her left flank. But she is broadly supported by most Democrats, whereas McCain’s appeal has mostly been with independents and for awhile, even many Democrats. Kerry wanted him as his running mate. The best example of a Democrat like him is Joe Lieberman.
As a result, according to Silver’s analysis, he probably did better than any other Republican would have. He might have even won if not for his poor judgment on a number of issues late in the campaign. Starting with his VP selection and ending with his decision to “suspend campaigning” in the wake of the fiscal crisis.
AS for Obama’s popularity, check out the approval numbers of Ike and Clinton. Pretty high, yet their wannabe successors couldn’t quite pull it off. Bush 41 is the only one of the last five to succeed, and he trailed by as much as 20 points at one point.
Clinton can certainly win, but anyone expecting this to not be a close race is kidding themselves. I’d actually expect Clinton to trail significantly at some point and cause a lot of bedwetting here.