Religious support for Clinton vs. Obama

A recent Gallup Poll found that among religious Democrats, Hillary Clinton enjoys more support than Barak Obama.

All in all, in interviews conducted Feb. 15-20 as part of Gallup Poll Daily election tracking, 57% of white, non-Hispanic Democratic voters who attend church support Clinton, while only 29% support Obama. Among those who attend church less frequently or never, Clinton’s support drops while Obama’s climbs.

This analysis is based on white Democrats. There is less of a relationship between candidate support and religion among black Democrats, who are both highly religious and highly likely to support Obama.

This seems a little counterintuitive, especially given Obama’s ability to speak easily and convincingly about his faith. What do you think accounts for the discrepancy?