Poll Madness: McCain Takes Lead Even As Democrats Out-Register Republicans?

Seth Colter Walls
The Huffington Post

This week's mainstream coverage of the presidential horse-race has been dominated by a series of polls showing the McCain-Palin ticket with its first stable lead over Obama and Biden. Gallup's tracking poll, USA Today and CBS News all show the Republicans with some kind of lead over the Democratic ticket. But, interestingly, all three polls were also conducted using a higher sampling of Republican voters than in July, raising a question of methodology.

In a year in which Democrats have a lead of 11 million registered voters over Republicans, and have been adding to that advantage through a robust field operation, are pollsters over-sampling Republicans?

Despite a raft of advantages in the electorate for Democrats, in September's first Gallup tracking poll, an equal number of Republicans and Democrats were surveyed (including "leaners") from Sept. 3-5, compared to a 10-point Democratic identification advantage two weeks ago. That partisan makeup of the polling pool resulted in a 5-point lead for McCain in Sept. 5 tracking poll. Meanwhile, the new CBS poll features a 6-point swing in partisan composition toward Republicans, which plays some role in the poll's two-point lead for McCain. Finally, the latest USA Today poll, which claims a four-point edge for McCain, was arrived at after a 10-point swing in partisan makeup toward GOP respondents.

(Continued here.)