Bill Quick does a nice job spelling out the apparent relationship between 2004 and 2008, Bush and McCain.
In short, the GOP establishment perceives the entire nation moving leftwards, and a long time ago made the decision to move the GOP to the left in order to keep in step with the culture at large. George Bush was the first of the “new breed” of GOP establishment characters to achieve the White House, with his doctrine of “compassionate” (liberal) conservatism. And it seemed to work. At least, it kept him in the White House for two terms, if only with razor thin wins each time.
