Early analysis: 88 House and Senate battleground races in 2020

In 2020, all 435 seats in the U.S. House and 34 of the 100 seats in the U.S. Senate are up for election. Our initial list of battleground races includes 88 of them—15 in the Senate and 73 in the House.
Battlegrounds are elections that we expect to have a meaningful effect on the balance of power in government or to be particularly competitive or compelling. 
In the U.S. Senate, where Republicans currently hold a 53-seat majority, Republicans are defending 22 seats while Democrats are defending 12. Of the 15 battleground races in this chamber, 10 are for seats held by Republicans and five are for seats held by Democrats. In 2018, there were 16 battleground races—11 held by Democrats and five held by Republicans.
In the U.S. House, Democrats hold a 237-197 majority with two vacancies. In the 73 battleground districts, Democrats hold 43 seats and Republicans hold 30. In 2018, there were 82 battleground districts—73 held by Republicans and nine held by Democrats. Fifty-seven of the battlegrounds districts in 2020 were also considered battlegrounds in 2018.
We selected this initial list of 2020 races based on past election results, whether the incumbent is seeking re-election, or was recently elected for the first time. We also considered race ratings from outlets like the Cook Political Report, Sabato’s Crystal Ball, and Inside Elections.