ABOUT THAT AP POLL…. A few credible national polls have been released over the last couple of days, and most of them offered similar results. NBC/WSJ shows Obama up by 10; Fox News has him leading by nine; ABC/WaPo puts Obama’s lead at 11; and Gallup shows an eight-point lead. Nothing especially shocking.

And then, there was that AP/GFK poll released yesterday, which threw a curveball at the political world.

The presidential race tightened after the final debate, with John McCain gaining among whites and people earning less than $50,000, according to an Associated Press-GfK poll that shows McCain and Barack Obama essentially running even among likely voters in the election homestretch.

The poll, which found Obama at 44 percent and McCain at 43 percent, supports what some Republicans and Democrats privately have said in recent days: that the race narrowed after the third debate as GOP-leaning voters drifted home to their party and McCain’s “Joe the plumber” analogy struck a chord.

These results conflicted with all of the other data we’ve seen of late. That doesn’t make it wrong, of course, but it does give one pause.

There may be a temptation on the part of some to believe polls that offer favorable results, and ignore polls that don’t. It’s not an intellectually honest way of watching a campaign, but it’s not uncommon. As such, there were more than a few conservatives who quickly seized on the AP poll as a very significant campaign development.

Are they right? There’s reason for skepticism. As Ambinder and Subday noted, 44% of those in the poll’s voter sample were self-identified evangelical Christians, who tend to be conservative Republicans. In the last presidential race, evangelicals constituted 23% of voters — about half the number used in the AP poll.

It’s possible, I suppose, that evangelical turnout will be higher this year, but a jump from 23% to 44%? It’s very unlikely. In fact, it’s practically impossible, and rather foolish to assume as part of the basis for a national campaign poll.

Anyone getting too excited (or too depressed) based on this AP poll is probably making a mistake.

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Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.