FairVote’s model of U.S. House of Representatives elections shows that House elections are so uncompetitive and skewed that it is unlikely that even a Clinton landslide would deliver Democrats the House.
Since 1998, FairVote has projected the results of upcoming congressional elections based solely on prior congressional and presidential election results. Without using any polling or campaign spending data, we were able to make high confidence projections for 80% of all congressional elections, which were accurate in 99.7% of races in 2012 and 2014 (we got one wrong). Indeed, even when we projected all 435 U.S. House seats, our accuracy rate was 96% for these two elections.
In order to emphasize that most House elections are uncompetitive regardless of Democratic or Republican waves, we model our official projections off an assumed 50-50 split in national two-party preference, which is closely related to the national popular vote, but calculated at the district level with third party and independent votes removed so as to focus on two-party partisanship. We have 362 high confidence projections (203 safe Republican seats, 159 safe Democratic seats) using data available from 2014, that remains steadfast even after considering 2016 election polling. Still, given that projections from FiveThirtyEight, The New York Times, Larry Sabato, and the Princeton Election Consortium show Clinton is headed for a landslide in the Electoral College, it is worth asking about the likelihood that this will win the Democrats the House of Representatives.
If the election were held today (10/19/2016), polls indicate that Clinton would win 53.9% of the national two-party vote, based on FiveThirtyEight’s nowcast. This is impressive, and is even higher than Obama’s national two-party vote in 2008 (53.7%), which gave Democrats 58.9% of seats in the House of Representatives. This election, however, by running our model using Clinton’s projected vote share as an estimate of national party preference, we can estimate that Obama’s 2008 margin would only yield 48.3% of the House, and Clinton’s projected margin would yield just 215 (49.4%) out of 435 seats.