Nate Silver: G.O.P. Has 2-in-3 Chance of Taking House, Model Forecasts

[t0dd]

Republicans have a two-in-three chance of claiming a majority of House seats in November, the FiveThirtyEight forecasting model estimates. And their gains could potentially rival or exceed those made in 1994, when they took a net of 54 seats from the Democrats.

In one sense, a strong performance by the Republicans on Nov. 2 is to be expected. The opposition party typically gains seats – on average, about 20 in midterm elections since 1994 – after the other party wins the White House, as the Democrats did in 2008. Nevertheless, both the magnitude of the Republicans’ potential gains, and the rapidity with which the political balance is poised to shift back to them after two cycles in which Democrats won nearly every competitive election, is unusual by recent standards. According to the model, Republicans have about a one-in-three chance of winning at least 54 seats, their total in 1994, and nearly a one-in-four chance of gaining at least 60.

Were the Republicans to achieve an outcome like that, one might need to look to the first half of the previous century for precedent; in 1948, for example, the Democrats added a net of 75 seats in the House, just two years after losing 54.

However, the headlines for this election have not yet been written, and there is considerable uncertainty in the outcome.

Several important national indicators, like the generic Congressional ballot, favor the Republicans. According to our analysis, Republicans have a lead of about 8 points on the generic ballot on the basis of likely voter models, which are generally more reliable in midterm elections than polls of registered voters (or of all adults). Meanwhile, President Obama’s approval ratings have been on a slow but steady decline for most of the 20 months of his tenure, particularly on the critical issue of the economy. On the basis of indicators like these, it is easy to envision Republican gains of 50 to 60 seats, or perhaps more, as some academic models that rely on these indicators do.

But FiveThirtyEight’s prediction model does not look solely at these national indicators. Instead, it evaluates the outcome in each of the 435 Congressional districts in which voters will cast ballots this fall. Although the generic ballot has some predictive power even at the local level, our analysis has found that it is not any more important – and in many circumstances, less important – than a series of metrics that can be applied to individual districts. For example, race ratings published by expert forecasters – and particularly those produced by Cook Political and CQ Politics – have an outstanding track record and are used extensively in our model. These forecasts generally point to a somewhat milder outcome for Democrats – perhaps a loss of about 40 seats.

http://fivethirtyeight.blogs.nytimes.com/2010/09/10/g-o-p-has-2-in-3-chance-of-taking-house-model-forecasts/#more-805

[notesdev]

1. next set of polls is going to be even worse

This mosque/koran-burning fiasco will be disastrous.