In the 2020 Senate race there are 35 senate seats up for election. These seats are the 33 class 2 seats up for regular elections, as well as the 2 special elections being held to fill the seats of the late senator John McCain as well as the seat of John Isakson who resigned. The republican party has 23 seats up for election while the Democrats have 12. Since Republicans currently hold the majority the Democrats will have to seize 4 seats to hold the majority in the senate or 3 seats and the presidency.
The states with senate seats up for election are as follows
Arizona (special election)
Georgia (both seats 1 regular 1 special)