Steve Waldman poses a question that has been gnawing at those of us who spend way too much of our time poring over exit polls by religious category; namely: Why didn't any more white mainline Protestants vote for Barack Obama? Like Steve, I expected Obama to make real inroads among his co-religionists, a onetime heartland Republican constituency that had been trending Democratic in recent elections. In the event, they voted (according to Pew's account), 55-44 for McCain (as opposed to 56-44 for George Bush in 2004.) Meanwhile, Obama reduced the Republican margin among white evangelicals, whom he wasn't supposed to be making headway with, by a full 11 points. What gives? Here's the best I can manage by way of an answer, based on currently available data.
Mainliners were the only Judeo-Christian grouping whose vote for Bush decreased from 2000 to 2004. And that decline occurred solely among those who attended worship frequently (once a week or more), to the tune of 8 percentage points. Bush actually picked up one percentage point among the less frequent attenders. (These data, worked up by John Green for an article in Religion in the News, can be found here.) We don't yet have the crosstabs for religious traditions by frequency of attendance in 2008, but we do know that among white Protestants, the evangelical portion of the vote increased (by three points), while mainliners dropped by a point. And in the overall attendance categories, there was a drop in turnout only among the more-than-weekly attenders. I'm guessing that the part of the mainline community that had not been in motion–the less frequent attenders–remained in place as it had in 2004, while among those who had been in motion–the frequent attenders–all that changed was that a small number decided not to vote for president this time around.
OK, but so what? My hypothesis is that 1) lukewarm mainliners have for the past decade been frozen into their partisan commitments in a way that may have more to do with where they live and what particular denomination they belong to than with their identity as generic mainline Protestants; and 2) worshipful mainliners reached a new partisan equilibrium in 2004, such that in 2008 just a few were sufficiently torn between conflicting impulses (economic conservatism, anti-Palinism, whatever) that they crossed their arms and stayed at home. Bottom line: White mainliners are now kind of like white Catholics–modestly more Republican than Democratic but less likely to shift around.
(Originally published at Spiritual Politics.)