In duelling rallies, President Donald Trump and President-elect, Joe Biden, have urged voters in Georgia to turn out for elections on today that will decide which party controls the Senate.
Mr Trump, a Republican, and Mr Biden, a Democrat, said the votes for two Senate seats would shape the US for years.
More than three million Georgians have already cast ballots – nearly 40 per cent of the state’s registered voters.
If the Democrats win, they will control all of Congress and the White House.
The Republican Senate incumbents in Georgia – Kelly Loeffler and David Perdue – are trying to hold off the Democratic challengers, Jon Ossoff and Reverend Raphael Warnock.
The runoff is needed under Georgia’s state election rules because none of the Senate candidates received more than 50% of the vote in November’s US election.
Voting begins at 07:00 AM and is expected to end at 7:00 PM.
The vote will decide the balance of power in the US Senate.
Republicans are currently in control, holding 52 of the 100 seats. If both Democrats win on Tuesday, the Senate will be evenly split, allowing incoming Democratic vice-president Kamala Harris the tie-breaking vote.