I've updated my projections for Senate and Gubernatorial outcomes, based on the historical relationship between polls and actual election outcomes in 2006 and 2008. The new tables (below) rank order the states by the magnitude of the predicted Democratic vote, and the shaded areas represent the closest predicted outcomes.
Here's where things stand right now. Based on point estimates alone, I project a Republican a gain of seven seats in the Senate and five governorships. While I don't see any potential Republican losses in the Senate, their gains in the gubernatorial races are blunted somewhat by expected losses of several currently Republican governorships: California, Connecticut, Florida, Hawaii, Minnesota, Rhode Island. Many of these projected outcomes, as well as some of the Democrat-to-Republican switches, are razor thin, so any sort of unspecified error that systematically biases projects toward one of the parties could produce significantly different aggregate results. It's also worth noting that two races, Colorado and Rhode Island, have strong independent candidacies that could upset the Democratic candidates, even if they beat their Republican rivals.
Gubernatorial Forecasts
On the Senate side, I don't see a lot to suggest that the picture will turn out very different from the projection of seven Democratic losses. To be sure, two seats pegged as switching, Illinois and Colorado, are close enough that a small change in poll results could push them into the Democratic hold column. At the same time, though, a couple of the projected Democratic holds, Nevada and West Virginia, could easily turn into Republican pickups.
Senate Forecasts
Note that all projections are based on polling averages from forty-five days prior to the election (September 18) and that polling data for the models and for the 2010 elections are from pollster.com.
