I haven't seen anybody make the point that what killed John McCain in the election was the Republican base. The rest of the country has drifted very far away from Republican dogma, but the base believes it more strongly than ever. This puts GOP politicians in an impossible bind.
Byron York had a good pre-postmortem about the McCain campaign a few weeks ago -- good in the sense of conveying the campaign's view of the world in a way few reporters had to date -- and this particular passage makes my point:
But the Bush Burden continued to drag on the campaign; the success of the surge did not change the president’s approval numbers. By January 2008, Bush was still in the low 30s, with disapproval in the mid-60s. It was the same on Super Tuesday. By October, as the campaign reached its final stages, Bush had sunk to 25, with a 70 percent disapproval rating. What to do? McCain received a lot of advice to distance himself from Bush. But he needed the votes of that 25 percent of the electorate that still approved of the president. And with Republican voters putting national security high on their list of concerns, was McCain supposed to throw over the man whose administration had kept the United States free from a major terrorist attack in the seven years after September 11? Bush had made some serious mistakes, but there was real danger in appearing to run away from him.
McCain either didn't want to run away from Bush, or wanted to but couldn't, because of the base's loyalty to him. So McCain was stuck semi-attached to the most unpopular president since the advent of polling. It's as if Democrats were trying to formulate a foreign policy platform in an environment where their base adored Osama bin Laden.
There are other examples. McCain just got killed among Latino voters. McCain actually has very moderate instincts on immigration, but he couldn't flaunt those instincts for fear of provoking the base that already distrusted him on the issue. Likewise on economics. McCain's biggest single liability may have been the fact that majorities of voters thought he would favor the rich, and that Obama would favor the middle class. MCain had once denounced Bush's tax policies explicitly on the grounds that they unduly favored the rich, but the base forced him to embrace those tax cuts and add even more tax cuts for the rich, to demonstrate the depth of his newfound conviction. And, of course, he needed to nominate Sarah Palin to energize the base, a choice that cost him dearly.