GLOOMY FORECAST: GOP HAS A 55% CHANCE OF WINNING THE SENATE

NATE SILVER, five-thirty-eight

The Senate playing field remains fairly broad. There are 10 races where we give each party at least a 20 percent chance of winning,¹ so there is a fairly wide range of possible outcomes. But all but two of those highly competitive races (the two exceptions are Georgia and Kentucky) are in states that are currently held by Democrats. Furthermore, there are three states — South Dakota, West Virginia, and Montana² — where Democratic incumbents are retiring, and where Republicans have better than an 80 percent chance of making a pickup, in our view.
So it’s almost certain that Republicans are going to gain seats. The question is whether they’ll net the six pickups necessary to win control of the Senate. If the Republicans win only five seats, the Senate would be split 50-50 but Democrats would continue to control it because of the tie-breaking vote of Vice President Joseph Biden.

Our March forecast projected a Republicans gain of 5.8 seats. You’ll no doubt notice the decimal place; how can a party win a fraction of a Senate seat? It can’t, but our forecasts are probabilistic; a gain of 5.8 seats is the total you get by summing the probabilities from each individual race. Because 5.8 seats is closer to six (a Republican takeover) than five (not quite), we characterized the GOP as a slight favorite to win the Senate.
The new forecast is for a Republican gain of 5.7 seats. So it’s shifted ever so slightly — by one-tenth of a seat — toward being a toss-up. Still, if asked to place a bet at even odds, we’d take a Republican Senate.

Of course, it can be silly to worry about distinctions that amount to a tenth of a seat, or a couple of percentage points. Nobody cares all that much about the difference between 77 percent and 80 percent and 83 percent. But this race is very close. When you say something has a 47 percent chance of happening, people interpret that a lot differently than if you say 50 percent or 53 percent — even though they really shouldn’t.³
It’s important to clarify that these forecasts are not the results of a formal model or statistical algorithm — although it’s based on an assessment of the same major factors that our algorithm uses. (Our
tradition is to switch over to fully automated and algorithmic Senate forecasts at some point during the summer.)



We usually begin these forecast updates with a broad view of the political landscape. Not all that much has changed over the past couple of months.

• President Obama remains fairly unpopular with an approval rating of about 43 or 44 percent. His numbers haven’t changed much since March (perhaps they’ve improved by half a percentage point). It may be that modestly improved voter perceptions about the economy are being offset by increasing dissatisfaction of his handling of foreign policy. Since the start of 2013, Obama’s foreign policy approval rating has dropped precipitously. And unlike his overall approval rating, it has shown no sign of recovering. It’s now more than 5 percentage points below his overall approval rating.

Over the past year and a half, the president has been bedraggled by foreign policy controversies, including his handling of the attacks in Benghazi, Libya, and their aftermath, the National Security Agency’s collection of data at home and abroad, Russia’s incursion into Ukraine, and, most recently, the prisoner swap for Sgt. Bowe Bergdahl.

Both Democratic and Republican voters report lower levels of enthusiasm today than they did in 2010 (perhaps for good reason). But Republican voters are more enthusiastic than Democrats on a relative basis. That will potentially translate to an “enthusiasm gap” which favors the GOP, but not as much as it did in 2010.

Republicans’ recruiting of viable candidates is going better than in 2010 and 2012 although not uniformly so: they face potential issues in Mississippi and Oregon, for instance.

The quality of polling is somewhat problematic. Much of it comes from firms like Public Policy Polling and Rasmussen Reports with dubious methodologies, explicitly partisan polling firms or new companies that so far have little track record. As a potential bright spot for Democrats, polling firms that use industry-standard methodologies seem to show slightly better results for them, on average. However, these high-quality polls are mostly reporting results among registered voters only, rather than likely voters. Thus, they aren’t yet accounting for the GOP’s potential turnout advantage.