Silver: GOP to Gain 50 House Seats
Nate Silver reports:
FiveThirtyEight’s projection for the U.S. House shows little change from last week. Republicans are given a 73 percent chance of taking over the House, up incrementally from 72 percent last week. During an average simulation run, Republicans finished with 227 seats, up from 226 last week; this would suggest a net gain of 48 seats from the 179 they hold currently.
However, there is considerable uncertainty in the forecast because of the unusually large number of House seats now in play. A gain of as large as 70-80 seats is not completely out of the question if everything broke right for Republicans. Conversely, if Democrats managed to see a material rebound in their national standing over the final two weeks of the campaign, they could lose as few as 20-30 seats, as relatively few individual districts are certain pickups for Republicans.
In past weeks, we have written about the divergence between the various indicators that the model uses — for instance, the generic ballot, as compared against polls of individual districts. Increasingly, however, these metrics are falling into alignment.
Some generic ballot polls have shown incremental improvement in Democrats standing — although they still trail by roughly 6 points among likely voters on the generic ballot, according to our model’s estimate. According to one commonly-used formula, a Republican lead of 6 points on the generic ballot would translate into a gain of about 50 seats.
Meanwhile, more and more polls of individual districts are being released (in excess of 150 districts have now received some type of polling this year). While it is somewhat difficult to determine whether these local polls show movement toward one party or the other over all, their relative abundance allows us to come to some general conclusions. For instance, 50 of the 73 districts that are closest to the national average in terms of presidential voting (those with a Partisan Voting Index of between R+3 and D+3) have been polled. The Republican candidate leads by an average of between 3 and 4 points in our adjusted polling average in these districts. Although many of the leads are small and the Democrat is ahead in our polling average in 18 of the 50, this nevertheless suggests that the “typical” House district slightly favors Republicans on the basis of local polling, which means that they are more likely than not to take a majority of the House over all.
Expert forecasts like those used by Cook Political are also employed in our model. These groups had been somewhat cautious before — but they have continued to move their forecasts in the direction of Republicans, and most of them are now suggesting a Republican gain closer to 45 or 50 seats than 35 or 40. These expert forecasts are now in strong alignment with the local polls. For instance, all 40 of the districts currently rated by a tossup by Cook Political have been polled. On average, our adjusted polling average of local polls in those districts show the two candidates essentially tied, with Republicans at 44 percent of the vote and Democrats at 43.
Finally, a poll of competitive districts conducted by National Public Radio — although it is not used directly in our model — is also consistent with an “over-under” line of a 50-seat Republican gain, according to an analysis by Glen Bolger of Public Opinion Strategies, who helped conduct the survey.
So, a broad array of indicators will get you somewhere in the vicinity of a 50-seat Republican gain — as does our model. Some wind up a little north of it and others a little south of it, but they paint a reasonably consistent picture.
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