Democrats will retain or regain control of the US Senate in 2022 during a Biden Presidency.

Both of the 2020/2021 GA US Senate Election runoffs are pure Tossups. History has been unkind to Democrats regarding winning the GA US Senate Election runoffs.
1992(Coverdall-R vs Fowler-D)
2008(Chambliss-R vs Martin-D)
Democrats will end up with 48 US Senate seats if they don't win both of the GA US Senate seats.
The most vulnerable Democratic held US Senate seats up for re-election in 2022 are-
AZ(Kelly-D) if Ducey-R runs, the race will be a Tossup.
NV(Cortez Masto-D) if Sandoval-R runs, the race will be a Tossup.
NH(Hassan-D) if Sununu-R runs, the race will be a Tossup.
Democrats need to win 5 Republican held US Senate seats up for re-election in 2022 to regain control of the US Senate in 2022.
1)PA(OPEN Toomey-R)
Democratic field is wide open.
Tom Wolf-D - outgoing 2 term Governor is the frontrunner if he decides to run.
John Fetterman-D,Josh Shapiro-D, or Joe Torsella-D
-low level statewide elected officials will either run for Governor or US Senators.
Brendan Boyle-D Philadelphia/Montgomery County area US House Member is the likely Democratic nominee if Wolf, Fetterman, Shapiro, or Torsella don't run.
2)NC(OPEN Burr-R)
Democratic field is wide open.
Anthony Foxx-D(Secretary of Transportation under Obama)former mayor of Charlotte is likely to be the Democratic nominee if he runs.
Jeff Jackson-D military veteran/state senator will perform better than what Cunningham-D did in 2020 against Tillis-R.
3)WI(Johnson-R)
Mark Pocan-D(Madison area US House Member) is the likely Democratic nominee if he runs.
4)GA(Loeffler-R)
Current Atlanta Mayor Keisha Lance Bottoms-D or GA-6cd(Atlanta suburbs) US House Member Lucy McBath-D will likely be the Democratic nominee instead of Ossoff and/or Warnock.
5)FL(Rubio-R)
Val Demings-D(Orlando area US House Member) is the likely Democratic nominee if she runs.