I did an interview with Stuart Varney, filling in for a vacationing Neil Cavuto. He used the first New Hampshire poll (Aug. 22) showing Scott Brown only two points behind Democratic incumbent Senator Jeanne Shaheen as a jumping off point for a description of the pre-Labor Day U.S. Senate forecast.
Brown remains an underdog to win the seat, but most forecasts using historical data and the latest polls still give Republicans a better than 50 percent chance to win six seats and take control of the U.S. Senate.
Up to late August, the forecasts are driven primarily by historical data. For example, weighing a senate race where Romney got more votes than Obama in 2012, to giving the Republican candidate an edge. But after Labor Day, the polls in each state will become dominant in the models and the Democratic strategy of running strong localized races, especially with incumbents, gets tested. There are two models from Democratic websites (Huffington Post and Kos) that show Democrats holding the senate. But, the mainstream sites (i.e., major papers, Nate Silver, etc.) still see Republicans with a slight edge to win six seats.
The different forecasts should converge, and it appears the races will tighten because several Democrats are indeed performing better than the forecasts predicted.