During an interview on NPR this morning, Matthew Dowd (chief strategist for Bush-Cheney '04) said that if McCain and his advisors were given truth serum, they would acknowledge that Obama is a much more formidable opponent than Clinton. The reasons Dowd gave are as follows: (1) Obama represents a new generation, whereas Clinton, like McCain, represents a return to the past; (2) Obama's position on Iraq has been clear and consistent; and (3) Clinton will unify the Republican base, but there's no vitriol on the right for Obama.
Dowd also expressed concern that McCain may be seen as pandering to the right if he has to keep going to right-wing groups to provide reassurance. He noted that McCain's campaign imploded last year precisely because that type of pandering presented such a jarring contrast with McCain's "Straight Talk Express" brand.