Gallup released a new poll Thursday headlined “Religious Whites Disproportionately Shift Away from GOP.” It’s perhaps the clearest indication yet that the Republican base is becoming disillusioned with the party.

An analysis of USA Today/Gallup poll trend data indicates that while Democrats have made gains across the board on the generic Congressional ballot in the latest Oct. 6-8 survey, the change has been greater among religious whites than among less religious whites and among non whites. At this point, religious whites are equally as likely to say they will vote Democratic as Republican, a marked change from their strong tilt towards the Republicans in surveys conducted June through September.

[…]

There are two main factors which determine election outcomes: the candidate preference of voters and the relative turnout on Election Day of each candidate’s supporters. Republicans have benefited historically from having a significant advantage in terms of the vote choice among religious whites over the years, and have in addition placed a good deal of effort on the attempt to get these individuals motivated enough to turn out and vote.

The data reviewed here suggest that the Republicans have lost — at least temporarily — some of the disproportionate advantage in voting preference they have enjoyed among religious whites. This group continues to be much more likely than less religious whites or nonwhites to support the Republican candidate in their House race, and is currently as likely to support a Democrat as a Republican Congressional candidate. But, the difference between religious whites and these other two groups has narrowed somewhat as of the Oct. 6-8 poll.

As with all Gallup polls* for USA Today, the main sample is merely of “adults,” with “registered voters” and “likely voters” mere subsamples. That presents some serious methodological issues when moving from simply guaging the public mood to predicting voter behavior.

That said, the methodology was presumably consistent across these polls and the trends are horrible for the GOP.

Further, while the magnitude of the shift is surprising, the direction is not. Between frustration that little progress has been made on the social issues despite the fact the Republicans have been in power for most of the last six years (minus the brief loss of Senate control caused by Jim Jeffords’ defection and the public’s ability to express their will at the polls again) and numerous scandals which call into question the degree to which the party really exemplifies “family values,” religious conservatives have to be disillusioned.

My guess is that Kevin Drum is absolutely right here: “In the end, I imagine that a majority of these people will hold their noses and vote for Republicans after all. But if even 5% of them stay home and another 5% switch to the Democrats, it’s going to have a huge impact.”

*Full disclosure: My wife is a VP at Public Opinion Strategies, another polling firm.