Given the lineup of seats up in the Senate, chances are Democrats will take the Senate if former vice president Joe Biden takes the presidency. All told, with maybe the exception of Iowa, every single state where Biden is leading also has the Democratic Senate candidate ahead. The average difference between the presidential and Senate margins in all the races is about 4.3 points. Indeed, 90% of the differences in the Senate margins across states can be explained by the differences in the presidential margins. When we incorporate the results from the 2016 presidential election into our measure of presidential margins, this 90% becomes 91%.

Source: CNN September 26, 2020 09:45 UTC