Interesting article from Slate magazine:
What is clear is that Barack Obama is pursuing a course radically different from Kerry's—or, for that matter, Al Gore's. (Gore lost the white evangelical vote by a 68-30 margin.) And therein lies a tale about one of the least appreciated but most effective of political techniques: the art not so much of winning over voters as of lessening the intensity of their opposition...
The reassurance strategy, by contrast, takes the opposition as a given and then tries to lower its intensity. To oppose a candidate, after all, isn't the same as actually giving money or pulling the lever for the other guy. White evangelicals in Ohio may well support John McCain by margins of 2-1—but if they're not out on Election Day with car pools and massive door-to-door vote pulling, that's a major victory for Obama.