How big could the GOP House majority get?

April 18

House Speaker John A. Boehner (R-Ohio) speaks during a briefing March 5, 2014, at the Republican National Committee headquarters in Washington. (Photo by Alex Wong/Getty Images)

In previous reports on our House forecasting model, we’ve noted two key things: Democrats have a very small chance of retaking the House in 2014 and, if anything, Republicans are more likely to gain seats than lose seats.  But how many seats could the GOP gain?  And with what probability?  Here’s a sense of what the model suggests.

To recap, the model is currently based on a set of structural features known to influence House races: the state of the economy, presidential approval, the fact that it’s a midterm year, the partisanship of the district, and whether the incumbent is running for reelection.  We’ll build more into this model soon — for example, fundraising — but even this simple model provides a useful sense of the landscape.  We’ve updated the forecast to reflect recent (modest) improvements in the economy (growth in GDP) and a small increase in presidential approval, as well as any new retirements.  The prognosis for Democrats isn’t any better: the median estimate is a small seat loss (to 196 seats).  The chance of their regaining the House is still very low — about 1%.

Simulations from the model can tell us more about the probability of specific outcomes.  Below is a chart giving the percent chance that the Republicans control various numbers of seats.

forecastinghistogram

The estimates are centered around a median of 239, which would represent a gain of 5 seats relative to the 234-seat Republican majority after the 2012 election.  (The GOP current controls 233 seats because of vacancies.)  Here is the associated likelihood of some other scenarios:

  • The Republicans control as many or more seats as they controlled after the 2010 election (242): 39% chance
  • The Republicans control as many or more seats as they controlled after the 1946 election (246): 24%
  • The Republicans control as many or more seats as they controlled after the 1928 election (270): 0.2%

Thus, based on the current model and current conditions, there is a real chance that the 2014 election could give the GOP as many or more seats as it had after the wave election of 2010.  There is less of a chance, though still a chance, that the GOP could command a majority as large as its post-WWII high-water mark.  But, as of now, 2014 appears unlikely to give the GOP the unprecedented majorities it had after 1928 (or after 1920 for that matter, when it controlled 302 seats).

As we’ve emphasized, this is a forecast based on current conditions and based on a limited set of factors.  As we incorporate more information about other factors — particularly those related to the candidates themselves, such as their political experience and fundraising — the forecast could change, as it might change if conditions shift in Democrats’ favor.  For example, there has been a small increase in Obama’s approval rating in the last few months.  If this were to continue, Democrats could do a bit better in 2014, although it is unlikely that Obama’s approval could carry them to a majority.

John Sides is an Associate Professor of Political Science at George Washington University. He specializes in public opinion, voting, and American elections.
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