Weigel nails the current campaign dynamic:
Not only are McCain's attacks all about character and weakness; Obama's responses basically validate them. That guy says I've got ladyparts and I hate America and want to raise taxes: In fact, I want to cut some taxes and raise others! Obama, accused of being a wimp, waves his calculator.
What could Obama do, though? There's a character case to make against McCain, whose shifting issue positions and bloated sense of self-importance are almost Obama-like. But every attack on McCain's character comes up against the iron wall of his POW days.
This is the irony of that weird meme of a few weeks back that Obama "couldn't take a joke" (after that New Yorker cartoon portraying him as a terrorist): It's McCain who can't be mocked without holy hell unleashing. When the host of one of the Sunday shows accusing a guest of "questioning McCain's integrity" for pointing out that he's changed positions, you've got a problem. The Clintons are/were better aggressive campaigners, but how would the sleaze and naked ambition of that family be matching up against this? The only hope the Democrats ever had of making this easy was a Mitt Romney nomination. That guy made Thomas Beatie look like John Holmes.