Nate Silver responds to the DSCC’s criticism:

Our forecasts could be wrong in November. In fact, they probably will be wrong — it’s unlikely that Republicans will win exactly six seats. But we think it’s equally likely that our forecast will be biased in either direction. If Democrats retain just one more seat, they’ll hold the Senate. Or Republican gains could grow to seven seats, or quite a bit more.

And here’s the least surprising news: Political campaigns are hypocritical. At the same time the DSCC is criticizing our forecasts publicly, it’s sending out email pitches that cite Nate Silver’s “shocking, scary” forecasts to compel Democrats into donating.

You’d do well to shut out the noise the next time the DSCC writes a polling memo.

Weigel believes that “the Silver backlash was inevitable”:

Silver’s cachet on the left, which was high after 2008, became incomparable after 2012. That was the year FiveThirtyEight became a digital security blanket for liberals, a site they could refresh and refresh and refresh some more when their other news sources warned them that Mitt Romney might actually win.

Cillizza offers a few reasons why Democrats are so worried about Nate Silver’s latest predictions:

Know who REALLY listens to what Nate says? Major Democratic donors. They follow his projections extremely closely and, if he says the Senate majority won’t be held, they take it as the gospel truth. That, of course, is a major problem for the DSCC and other Democrats focused on keeping control of the Senate — particularly given that major outside conservative groups led by Americans for Prosperity are already spending heavily on ads bashing vulnerable Democratic incumbents. If the major donor community concludes that spending on the Senate isn’t a worthy investment, [Guy] Cecil and his Democratic colleagues know that their chances of holding the majority get very, very slim. Nate’s predictions move money in Democratic circles. Cecil knows that. Hence the memo.

Kilgore tries to stay optimistic:

Comparing 538’s forecast to its most credible rival, the Cook Political Report, is instructive. Cook’s Jennifer Duffy lists Arkansas as a toss-up race; Nate shows a 70/30 probability that Mark Pryor will lose. Similarly Cook shows the two vulnerable Republican seats, Kentucky and Georgia, as toss-ups. Nate gives Democrats a 25% chance of winning Kentucky and a 30% chance of winning Georgia. But his numbers would change rapidly with a few more likely-voter surveys in any of these states showing Democrats running even or ahead; Duffy tends to project races as very close until evidence emerges that they are not so close.

But there’s not a great deal of divergence in the factors used by 538 and Cook—polls, electoral history, money, national trends—and it’s very likely their forecasts will converge as we get closer to November.