Democrats have flipped two Republican Senate seats this cycle, while Republicans flipped one seat held by a Democrat. The current balance of power stands at 48-48, with four races outstanding, two of which are in Georgia.

A special election there has already gone to a runoff, which will be held Jan. 5 between incumbent Republican Sen. Kelly Loeffler and Democrat Raphael Warnock. The other race, pitting incumbent Republican Sen. David Perdue against Democrat Jon Ossoff, also has the potential to go to a runoff in January, which means balance of power in the Senate might not be determined until after the next Congress convenes on Jan. 3.

Also outstanding is the Senate race in Alaska where Republican incumbent Sen. Dan Sullivan is expected to win easily. With roughly 50 percent of the expected vote counted, Sullivan has a 30-point lead on his Democratic challenger, Al Gross.

And finally, the North Carolina Senate race between Republican incumbent Sen. Thom Tillis and Democratic challenger Cal Cunningham is still too close to call, with 93 percent of the expected vote counted.

Democrats need to win 50 seats in the Senate to have majority control if Joe Biden wins the presidency, which would give Vice President Kamala Harris the tie-breaker vote in the upper chamber, and 51 seats if President Donald Trump wins a second term.