Heading into the summer, it was clear that George W. Bush was John McCain's biggest liability. Of all the negative characteristics polled about the candidates at that time, the one that drew the most concern from voters was McCain's similarities to Bush. It was more problematic than Obama's connections to Jeremiah Wright and Bill Ayers, even.
Today, that's changed. Sarah Palin is now the heaviest anchor around the neck of John McCain's sinking campaign. From First Read:
...her numbers have plummeted in our poll. For the first time, she has a net-negative fav/unfav rating (38%-47%), the only principal to carry that distinction. What's more, 55% think she's unqualified to serve as president if the need arises, which is a troublesome number given McCain's age. (Have worries about McCain's age risen because of Palin? Seems to be the case). In fact, her qualifications to be president rank as voters' top concern about a McCain presidency -- ahead of continuing Bush's policies. (Who would have ever thought that Palin would be a bigger problem for McCain than Bush would?)
The distinction to make, of course, is that McCain couldn't really do anything about his similarities, real or perceived, with Bush. He brought Sarah Palin on himself.