Nate Silver: Republicans are favored to take the Senate

The FiveThirtyEight Senate model is launching Wednesday. We’ll be rolling it out in stages, with additional features, functionality and further methodological detail. We’ll also be unveiling our new set of pollster ratings and publicly releasing our database of all the polls used to calculate them. So there’s a lot more to come.

But if you’re looking for a headline, we have two. First, Republicans are favored to take the Senate, at least in our view; the FiveThirtyEight forecast model gives them a 64 percent chance of doing so.

The reasons for the GOP advantage are pretty straightforward. Midterm elections are usually poor for the president’s party, and the Senate contests this year are in states where, on average, President Obama won just 46 percent of the vote in 2012.¹ Democrats are battling a hangover effect in these states, most of which were last contested in 2008, a high-water mark for the party. On the basis of polling and the other indicators our model evaluates, Republicans are more likely than not to win the six seats they need to take over the Senate. This isn’t news, exactly; the same conditions held way back in March.  (Continues)