Look, part of the problem for McCain isn't just the negatives against him. It comes down to the basic question: What will you do once you're in office? He has yet to seriously answer the question. Obama has yet to answer it either, but he's still got the aura of an outsider, even though he's benefitted from the Chicago political machine, and has yet to ever speak out against it. (In fact, IIRC, he's actually gone against reformers who wanted to tear the whole rotten mess down.)
Hillary Clinton at least offered a look at what it was she wanted to do, and how she'd get there. That the votes from Florida and Michigan were unceremoniously dumped by the Democratic Party, and the delagates parsed out, leaves me wondering just how much better she might have been doing. My suspicion is that she'd be ahead, and the lead would be far more solid. At this point, I don't know that Obama's lead is really as firm as we're led to believe. Things can change in a heartbeat in this year, and McCain could still pull it out if he'd act as though he were a leader, rather than a petulant kid whose mother told him he couldn't have the cereal with the prize in it.