Larry Sabato

Based on information gathered in June, our forecast for 2018 is that the Democrats will gain seats in the House and most likely enough to retake control. The predicted seat division may surprise given that we expect the Democrats to win the national vote by a substantial margin (53.6%-46.4% as a two-party share). First, using past elections as a guide, we model the national vote as a function of the generic ballot polls four-to-five months before the election, plus which party holds the presidency. Second, using the most recent election (2016) as a guide, we model how the vote in individual seats varies as a function of the vote for the House and the president in the most recent election.

The map benefits Republicans in both the battle for the House and the Senate: The median House seat by presidential performance (NE-2) voted for President Donald Trump by two percentage points, while Hillary Clinton won the national popular vote by two, making the median House seat about four points to the right of the nation, which is a good shorthand for the generic GOP edge in the House. The president’s approval rating, while poor, has not gotten worse in recent months; the House generic ballot, generally showing a Democratic lead of between six-to-eight points, is bad enough to indicate Republicans could lose the House, but not bad enough for that to feel like a certain outcome. Republicans selected Rep. Ron DeSantis (R, FL-6), who rode support from President Trump to a big win over one-time clear frontrunner Adam Putnam (R), the state agriculture commissioner and a former U. S. House member. Meanwhile, Democrats eschewed seeming favorite Gwen Graham (D), a former House member herself and daughter of former Florida governor and senator Bob Graham (D), in favor of Andrew Gillum (D), the African-American mayor of Tallahassee who ran to Graham’s left with the backing of Sen. Bernie Sanders (I-VT).

The University of Virginia Center for Politics and Ipsos today launched the UVA Center for Politics-Ipsos Political Atlas. The new site combines Sabato’s Crystal Ball race ratings for every House, Senate, and gubernatorial race; Ipsos’ poll-based modeling; and Ipsos’ tracking of social media trends. The idea behind the Political Atlas is that election projection is done best by offering readers several different sources of information, which the Atlas provides through the Crystal Ball’s qualitative race rating assessments and the Ipsos’ poll-based model and social media tracking. The Center for Politics and Ipsos released two polls on Americans’ attitudes toward recent presidents, and the Center and Ipsos, along with Reuters, released a poll last month on Americans’ racial attitudes at the time of the one-year anniversary of a neo-Nazi march in Charlottesville, as well as a poll on racial attitudes conducted in the aftermath of that march.

Here for each cycle, there appeared to be a real difference between incumbents and open seats in their averages and on the range of results for open seats being lower. Here, I compare the median relative down-ballot performance for each seat based on the status of that seat, here showing it by party and number of incumbent terms. It’s a bit lower going from an open seat to the same party, but higher than an incumbent winning another race, so an open seat penalty here is still applicable. There’s not a large sample in here, but we can take a look at whether incumbents that have been around longer have a larger open seat penalty when they leave and it becomes an open seat.