Have Republicans peaked?
For the weeks of July 12-18 and July 19-25, the Gallup Organization's weekly aggregation of daily tracking polls showed Democrats ahead among all registered voters on the generic congressional ballot test question by 6 points (49 percent to 43 percent) and 4 points (48 percent to 44 percent), respectively. Each poll canvassed more than 1,500 registered voters nationwide. For the uninitiated, the generic ballot test question tries to approximate what the popular two-party vote will be nationwide and, over time, it has closely corresponded to the outcome on Election Day.
Gallup noted that this was the first time that either party has held an advantage of this size for two consecutive weeks. In the 21 weeks that Gallup has asked the generic ballot test question this year, the two parties have averaged a tie. It should be noted, however, that polls of registered voters inherently tilt Democratic by 4 or 5 points compared with polls of likely midterm election voters. Voter turnout for midterm elections is about a third less than it is in presidential years, and midterm voters tend to be whiter and older, two problem population groups for Democrats this year. . . .
First, I looked up the Gallup info, and I think that he read the material a little too quickly. Gallup's claim was based on one poll that Gallup does, not on an aggregation of polls (see this picture).
Gallup's poll also was unique in showing that Dems were improving. The RealClearPolitics average of polls over the same period shows that things are actually getting better for Republicans.
Two other points should be made Gallup is using a poll of registered voters, not likely voters. As Cook notes, one has to discount the Dems showing in such a poll: "If Democrats are running 4 or 5 points ahead among registered voters, it would mean a very, very close contest for control of the House." Likely voters are more likely to be Republicans in general. This year there is probably much more of a gap than usual because as one breakdown by Gallup shows there is a huge Republican advantage in enthusiasm.
All that said, Republicans were recently looking to pick up 11 governorships and now it looks like 8, Colorado is a mess and Maryland and California have moved slightly towards the Democrats. All that said, it is too hard to keep track of what all the polls are showing regarding likely voters as well as voter intensity. My guess is that the media bias is going to play an important role in these elections.