Everybody could be wrong like in November 2016….
But it doesn’t seem like THAT is the case this time….
Democrats are favored to gain control of the House of Representatives in this year’s midterm elections, according to the FiveThirtyEight forecast model. But — a very FiveThirtyEight-ish sentence follows — the range of possible outcomes is wide and Democrats’ prospects are far from certain. Relatively small shifts could allow Republicans to keep control of the House, or could turn a blue wave into a tsunami.
What’s behind all of this? Our methodology post goes into a lot more detail about how our forecasts are calculated. But that explanation is rather abstract, so in this article, I’m going to focus on how these factors are playing out given what we know about the political environment this year.
Theme No. 1: A broad consensus of indicators point toward Democrats performing well
In contrast to our presidential forecasts, which are heavily dependent on polling, our House model uses a broad mix of polling and non-polling indicators, including factors such as fundraising totals and historical trends in midterms. Those indicators look both pretty good for Democrats and remarkably consistent with one another:
- The Lite version of our forecast, which focuses as much as possible on district-level and generic ballot polls, projects Democrats to win the popular vote for the House by 7 or 8 percentage points.
- The Classic version of the model, which incorporates a lot of non-polling metrics such as fundraising and past voting in each district, also shows Democrats winning the popular vote by 7 or 8 points.
- The generic ballot, which influences all three versions of our forecast, has generally shown Democrats with a lead of … 7 to 8 percentage points.
- And finally, our model calculates a starting assumption about the race based on historical trends in midterms since 1946 and presidential approval ratings. It also implies that Democrats “should” win the House popular vote by about 8 percentage points — just what the other metrics show…..