Steve Waldman had a good post yesterday on how, for all the endless chatter about evangelicals, it's with mainline Protestants that Obama is really making hay. All I'd add directly to what he says is that mainliners have been trending in a Democratic direction for a few election cycles now--and, indeed, it does seem directly related to evangelicals. The more evangelical the GOP seems--as in the selection of Sarah Palin--the more they head in the other direction. They're kind of like Jews that way.
More generally, it does seem to me that there's been a good deal too much attention devoted to taking the partisan temperature of evangelicals this election cycle. Between the wishful thinking of an Amy Sullivan and the insistence of a Jim Wallis that yes, Virginia, there are progressive evangelicals--not to mention the decades' old liberal hope that the religious right would just go away--we've been mesmerized by the prospect of white evangelicals switching sides. Real politics means focusing on big groups that are evenly balanced, and which therefore are actually likely to swing one way or another--and that means mainliners and white Catholics. OK, and maybe evangelicals in the Midwest, some significant number of whom just might be prepared to cross party lines and vote this year for a liberal mainliner who hails from their part of country.