35 of the 100 Senate seats were up for election in 2020. At the time, Republicans held a majority in the Senate with a 53-47 balance. However, the Senate was vulnerable because 23 of the 35 seats were held by Republicans, while only 12 seats were held by Democrats. It was essential to hold the Senate to serve as a check against House Speaker Nancy Pelosi and a highly political Democrat-controlled House.
For the November 3rd General Election, two seats could not be called, leaving the Senate with a confirmed 50 Republicans and 48 Democrats. In a highly unusual scenario, both of these undecided seats came out of Georgia where Republican Senators David Perdue and Kelly Loeffler were up for re-election but had failed to pass the state’s mandatory 50% threshold. This led to a runoff election on January 5, 2021 in which incumbent Republicans faced Jon Ossoff and Rev. Rafael Warnock respectively.
The Republicans only needed to win one seat to retain their lead in the Senate, but they lost both.