Nate Silver @NateSilver538
Rs have a few of these districts too, but Ds have more, and in more competitive districts. This is worth around 1.0 to 1.5 points in popular vote margin for Rs, e.g. an 0.5-point R lead on the generic ballot would translate to a ~2 point pop vote win *even if polls are unbiased*. — PolitiTweet.org