Republicans still have slight edge in latest Nate Silver Senate forecast

Nate Silver, the reigning champion of election forecasting, has issued a new Senate forecast. He projects that the Republicans will gain 5.7 Senate seats. They need a gain of 5 to wrest control of the Senate, so Silver’s forecast gives the Republicans a better than 50 percent chance of accomplishing this.

In his last forecast, Silver projected a Republican gain of 5.8 seats. Thus, he sees the overall shape of the election as essentially unchanged since March.

Silver finds, though, that certain races have changed shape — some in favor of the Democrat; others in favor of the Republican. One such race is in Arkansas:

In March, we gave Arkansas Sen. Mark Pryor just a 30 percent chance of holding his seat for Democrats. But five of the seven polls since then have put Pryor ahead of his Republican opponent, Rep. Tom Cotton.

Does that mean Pryor should be thought of as the favorite instead? Not quite, in our view. Most of the polls showing him ahead are among registered voters. Also, it’s not necessarily wise to dismiss earlier polling, most of which showed Cotton with the lead. There can sometimes be temporary fluctuations in the polling, as candidates, for example, buy a large amount of advertising but then revert to the mean.

Pryor is also running for re-election in a state where Barack Obama’s approval rating is somewhere in the mid-30s. However, it seems clear that Pryor has done a better job of separating himself from the national environment than former Sen. Blanche Lincoln did four years ago, and we now have his chances at 45 percent.

Democratic prospects have also improved significantly in Michigan, Silver finds. But Republican prospects are appreciably better now in Iowa, as I suggested earlier this week (Silver’s March forecast predated the revelation of Democrat Bruce Braley’s disparagement of Sen. Grassley).

Finally, what about Mississippi? In that race, from which I have generally averted my eyes, the Republicans may be about to dump Sen. Thad Cochran in favor of the more fiery, controversial, and conservative Chris McDaniel. Moreover, the Democrats have come up with a candidate who is regarded as “reasonably good and moderate.”

Here is Silver’s take:

First, let’s assume for a moment that McDaniel wins the runoff. While he might be “too” conservative for some states, Mississippi is very conservative itself. McDaniel would probably also have to make gaffes or misstatements on the campaign trail, as Richard Mourdock did for the Republicans in Indiana in 2012, or create trouble for himself.

Second, Mississippi is not just conservative but highly “inelastic”, meaning that there are few swing voters there and it can be hard for any Democrat to cobble together a 50 percent coalition. Third, McDaniel still has to win the runoff for Childers to even have a chance at winning, and that might not happen.

The race could badly use some better polling: all we have on the McDaniel-Childers matchup is a Rasmussen poll from March and a Public Policy Polling survey from November (not two of our favorite polling companies). For now, we have Childers’ chances at 10 percent in Mississippi, up from 5 percent before, on the assumption that he’d have perhaps a 20 percent chance against McDaniel but almost none against Cochran.

For me the key here is that McDaniel would probably have to make gaffes or misstatements on the campaign trail in order to lose this election. One hopes the factions that are promoting McDaniel so vigorously have vetted him to the point that Republicans can have confidence that he won’t self-destruct.

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