It's a shocking result. According to the Gallup Poll, a generic Republican candidate currently leads a generic Democratic candidate by 17 points among likely voters in a hypothetical House matchup. A margin of that magnitude on Election Day would almost certainly result in a Republican gain of at least 80 seats in the House of Representatives and the largest GOP majority since the 1920's. But how plausible are Gallup's results?
An examination of some of the internals from the latest Gallup survey of likely voters leads to the conclusion that these results are wildly implausible. First, Gallup shows a much larger percentage of Republicans (55% Republican identifiers and leaners vs. 40% Democratic identifiers and leaners) and conservatives (51% conservative vs. 28% moderates and 18% liberals) than we've ever seen in a modern election. They also show a smaller percentage of voters under the age of 30 (7%) and a larger percentage of voters over the age of 65 (27%) than we've seen in any modern election. But that's not all. The candidate preference results for some subgroups of voters are just wildly implausible.
Gallup's latest likely voter survey shows a generic Republican leading a generic Democrat by a whopping 28 points among whites, 62% to 34%. To put those numbers in perspective, in 1994, according to national exit poll data, Republicans only won the white vote by 16 points, 58% to 42%, and that was their best showing since the advent of exit polling. Gallup is telling us that right now the Republican lead among whites who are likely to vote is 12 points larger than the GOP margin among whites in 1994.
But that's not the most implausible result in the latest Gallup likely voter survey. Among nonwhites other than blacks, a group that comprises about 13% of likely voters, a generic Republican is leading a generic Democrat by 10 points, 52% to 42%. That's a group that voted Democratic by a 2-1 margin in the 2006 midterm election. Moreover, it's a group that has never given a majority of its vote to Republican candidates for Congress in any election since the advent of exit polling. According to the 2006 exit poll results, about two-thirds of these "other nonwhite" voters are Latinos. How plausible is it that at a time when the Republican Party is closely associated with stridently anti-immigrant policies that Latino voters are moving in droves toward Republican candidates? Not plausible at all, especially when Gallup's results are directly contradicted by other recent polls of Latino voters.
The Gallup Poll should be commended for making their internals available to interested observers for secondary analysis -- few other polling organizations are so generous with their data. And to be fair to Gallup, they have cautioned that these results are not a prediction of what will happen on Election Day, only a snapshot of current voter attitudes. But what is the value of putting out results that defy logic but which can influence perceptions of the current electoral climate among political elites as well as the public?