August 25, 2010, 12:45 pm
New Forecast Shows Democrats Losing 6 to 7 Senate Seats
By NATE SILVERThe Democratic majority is in increasing jeopardy in the Senate, according to the latest FiveThirtyEight forecasting model. The Democrats now have an approximately 20 percent chance of losing 10 or more seats in the Senate, according to the model, which would cost them control of the chamber unless Gov. Charlie Crist of Florida, who is running for the Senate as an independent, both wins his race and decides to caucus with them.
In addition, there is an 11 percent chance that Democrats will lose a total of nine seats, which would leave them with 50 votes, making them vulnerable to a defection to the Republican Party by a centrist like Joseph I. Lieberman of Connecticut or Ben Nelson of Nebraska. On average, over the model’s 100,000 simulation runs, the Democrats are projected to lose a net of six and a half Senate seats, which would leave them with 52 or 53 senators. (Even though the G.O.P. primary in Alaska remains too close to call, that outcome is unlikely to alter the model.)
The forecasts are based on a program designed to evaluate current polling and demographic data, and to compare these present-day conditions to outcomes in United States Senate races over the past six election cycles. For instance, in recent cycles, a Senate candidate with a 7-point lead in the polls 10 weeks before the election won about 80 percent of the time, and a candidate with a 12-point lead won about 95 percent of the time. Although the model, which correctly predicted the outcome of all 35 Senate elections in 2008, is not quite this cut-and-dried, it is this recent track record that forms the backbone of its projections.
Of late, the source of the Democrats’ problems has not necessarily been in high-profile Senate races where the Republicans have nominated inexperienced but headline-grabbing candidates, like Sharron Angle in Nevada and Rand Paul in Kentucky (although the model regards both Ms. Angle and Mr. Paul as slight favorites). Instead, it has been in traditional swing states like Missouri, New Hampshire, Ohio and Pennsylvania. The last time the Democratic nominee in Ohio, Lee Fisher, held the lead in any state poll, for example, was in June. Representative Joe Sestak, the Democratic nominee in Pennsylvania, has not led any poll there since May, and Robin Carnahan of Missouri has not held a lead since January. The Democratic nominee in New Hampshire, Representative Paul W. Hodes, has not led in any of 17 public polls in New Hampshire against his likely Republican opponent, Kelly Ayotte.
http://fivethirtyeight.blogs.nytimes.com/2010/08/25/new-forecast-shows-democrats-losing-6-to-7-senate-seats/Map:
http://elections.nytimes.com/2010/forecasts/senate