An early forecast from Alan I. Abramowitz over at Larry Sbabto’s political blog…..
In the last election, Democrats won 235 seats in the House of Representatives to 199 for the GOP with one vacancy remaining to be filled in a special, do-over election in North Carolina’s Ninth Congressional District. Republicans won a 53-47 seat majority in the Senate, with 34 seats up for grabs in 2020. Of those seats being contested, 22 are currently held by Republicans and 12 are currently held by Democrats. Republicans would need a pickup of 18 or 19 seats in the House, depending on the results of the special election in North Carolina, to take back control of the lower chamber and Democrats would need a pickup of three or four seats in the Senate, depending on which party controls the vice presidency in 2021, to take back control of the upper chamber.
In order to assess the outlook for the 2020 House and Senate elections, I used a forecasting model that provides fairly accurate predictions of seat swing based on four factors: the number of seats currently held by the president’s party, the president’s net approval rating in late August or early September of the election year, the results of generic ballot polling in late August or early September of the election year, and a dummy variable distinguishing midterm elections from presidential elections. Based on election outcomes in the post-World War II era, we expect that….
…
Barring a dramatic shift in the electoral landscape, Democrats appear very likely to hold onto their majority in the House of Representatives in the 2020 elections and make at least modest gains in the Senate. However, there are significant caveats with both projections. Obviously, one of those is that it is very early and that the president’s approval rating and the generic ballot could very well be different late next summer.
In the House, we are in an era with limited ticket-splitting and a weak incumbency advantage. Additionally, the overall House map has a Republican lean: Republicans could win the House back by defeating fewer than two-thirds of the 31 Democrats who hold seats that Trump carried in 2016 (and only three Republicans hold seats that Hillary Clinton carried). The confluence of these factors could allow Republicans to overperform the projection in this model, particularly if Trump is reelected.
While the model predicts a good chance of a Democratic majority in the Senate in 2021, that prediction should be taken with considerable caution considering the margin of error of the model and the fact that only a handful of Republican seats that are up next year are in Democratic-leaning or swing states. Moreover, if Democrats do take back the Senate, it will almost certainly be by a very narrow margin, which would make it difficult to pass the sort of progressive legislation advocated by many of the party’s 2020 presidential candidates…..