Control of US Senate hangs in the balance

[Moveon]

There are 4 senators that will become very very powerful in the next 2 years........

Can you name them. you already named one

All I know is that there are not 48 Dems, two independents that caucus with the Dems and 50 GOP Senators, and one Dem who is the VP elect right now and after the 20th will be the President of the US Senate as all VP do.