Things just keep getting worse for the Democrats in the senate. We now have the Democrats at just 19% to hold onto the senate. The amazing thing is that the continuous slide is not any serious slip-ups, but just the gradual shifting of leaning Republican to strong Republicans and one (or two) big surprises.
First, it was never really likely that the Democrats were going to carry Georgia, Alaska, Louisiana, South Dakota, Kentucky, or Arkansas. Several of the seats were blue, but the states are red. Over the last few months anything thing should be red, has just gotten a little redder, and that cements as time goes by. It is nearly Election Day and there have been no campaign altering incidents (i.e., no talk of rape, like Mourdock in 2012, or macaca, like George Allen in 2006).
Second, Colorado, a blue state, is proving very difficult for the Democrats in the polls; both the senatorial and gubernatorial incumbents are losing. I do not have a great explanation for this, but it is consistent in both races. I have heard arguments on both sides and feel confident in saying it is equally likely the polls are off in either direction; there is no reason, ex-ante, to assume the polls are off in the direction of the Republicans.
Third, Iowa is still a wild card in that it is both very tight and Ernst is very conservative and her handlers appear worried about her talking unscripted. A few hours ago she skipped her planned meeting the editorial board of the largest paper in Iowa. The 27% in Iowa reflects the uncertainty in the polls, there is slightly additional uncertainty in the candidate that the model is not capable of fully realizing.
Here is New York Times and FiveThirtyEight compared with PredictWise: