2018 US Election Predictions

Alex McHaddad, November 4, 2018

US House of Representatives

Democrats lost control of the House of Representatives in 2010, and Minority Leader Nancy Pelosi has long sought to reclaim the Speaker's gavel. In 2018, Democrats appear to finally have a shot at taking the House.

  • 190: Districts with higher Democratic than Republican turnout during primary season, or no GOP opponents
  • + 39: Districts with more registered Democrats than registered Republicans
  • = 229: Total districts with higher Democratic primary turnout or Democratic voter registration advantage

Republicans fair poorly in these counts, with higher primary turnout in 145 Districts and a voter registration advantage in 13 others.


The popularity of several blue state GOP Governors, including Charlie Baker in Massachusetts, Larry Hogan in Maryland, and Phil Scott in Vermont, makes the primary participation model less reliable for predicting gubernatorial contests. Victory in most contests, however, will likely correlate with primary turnout.

  • 15: Republican turnout was higher than Democratic turnout in 15 primaries. The exit of non-affiliated Alaska Governor Bill Walker is likely to result in a Republican victory in that state.
  • 20: Democratic turnout was higher than Republican turnout in 21 primaries. However, Governors Charlie Baker, Larry Hogan, and Phil Scott all overcame massive primary turnout gaps in their previous elections, however.
  • 3: Democrats held no primary in South Dakota, and Republicans held no primary in New York. Major parties in the Northern Mariana Islands chose their candidates at conventions.

US Senate

Despite their problematic house map, Republicans are likely to gain seats in the US Senate. 35 seats are up for election, including special elections in Minnesota and Mississippi. The later state is holding a jungle primary on election day in which the candidate with more than 50% automatically takes the seat; without such a victory, the top 2 candidates will face each other in a runoff. Maine Senator Angus King, a non-affiliated candidate who caucuses with Senate Democrats, is running against nominated candidates from the two major parties. In 4 additional states, only one major party held a primary, and no primaries were held in New York.

  • 11: Primaries with higher Republican participation. 42 Republican seats are not up for reelection, likely resulting in a GOP majority of at least 53.
  • 17: Primaries with higher Democratic participation. Despite likely winning more victories, only 23 Democratic seats are not up for reelection, likely resulting in a Democratic minority of 47 at most.