Famed statistician and political prognosticator Nate Silver is predicting that the Republicans are the slight favorites to take control of the senate in the 2014 midterm elections.

Silver’s data-based journalism site FiveThirtyEight relaunched last week with new backing from ESPN and made its first prediction about this year’s midterm elections since last July. Silver says current polling suggests the GOP will win at least six seats in the Senate, enough to give them an overall majority.

Silver, the founder and editor-in-chief of FiveThirtyEight, correctly predicted the winner of all 50 states and the District of Columbia in the 2012 presidential election battle between President Barack Obama and Republican contender Mitt Romney. That same year, Silver correctly predicted 31 of 33 U.S. senate races. He announced in 2013 that FiveThirtyEight would move from The New York Times to become a standalone site under the auspices of ESPN.

According to FiveThirtyEight, here’s what would need to happen for the Republicans to take advantage of the drop in Obama’s approval ratings and win the senate:

Republicans have great opportunities in a number of states, but only in West Virginia, South Dakota, Montana and Arkansas do we rate the races as clearly leaning their way. Republicans will also have to win at least two toss-up races, perhaps in Alaska, North Carolina or Michigan, or to convert states such as New Hampshire into that category. And they’ll have to avoid taking losses of their own in Georgia and Kentucky, where the fundamentals favor them but recent polls show extremely competitive races.”

However, Silver says that it “wouldn’t take much” for the Democrats to recalibrate in the coming months and pull ahead.

Write to Eliana Dockterman at eliana.dockterman@time.com.