At FiveThirtyEight, Nate Silver has published his first official Senate forecast of the year, and it gives Democrats some good news:
[T]he odds of a favorable overall outcome for Democrats have increased in recent weeks. The forecast model now gives them a 70 percent chance of controlling the chamber, either by having at least 50 seats and the presidency, or 51 without it.
Although this represents the first official FiveThirtyEight forecast for the Senate this year, I ran backdated forecasts to July 1 based on the polls that were available at that time. Two weeks ago, for example, the model would have given Democrats a 52 percent chance of retaining Senate control — and four weeks ago, it would have given them a 39 percent chance.
The trend toward Democrats is a relatively recent one. Part of the shift may reflect the bounce President Obama received from the Democratic convention. If so, it could recede, especially if Mr. Obama’s poll numbers do so, too.
But our analysis also suggests that the Democratic advantage has probably been building over the past few weeks, and may not have any one root cause. Instead, Republicans risk death by a thousand cuts, with a gradual deterioration in their standing in several important races, and their inability to field optimal candidates in others.
As Nate's last graph indicates, it's a complicated landscape, so you should read the whole thing. But factors boosting Democratic prospects include the Missouri fiasco, strong recent poll showings by Sherrod Brown, Bill Nelson and Elizabeth Warren, and the strong winds behind the candidacies of Martin Heinrich in NM and Mazie Hirono in HI.
Don't pop the champagne yet though. The SuperPacs are comin' Recent reports suggest that they might be taking money away from Romney and focussing on the Senate, House, and even loacl races. And that's a LOT of money.