Polls closed Tuesday evening in a pair of critical election runoffs in Georgia, whose outcome will decide who controls the US Senate and shape the early course of Joe Biden's presidency.

Joe Biden
US President-elect Joe Biden campaigned in Georgia on January 4, 2021 for two Democrats challenging Republicans in elections that will determine which party controls the US Senate Photo: AFP / JIM WATSON

The hard-fought races have brought the international spotlight onto this southern state, nine weeks after the most tumultuous US election in two decades.

Democrats need both their candidates, Jon Ossoff and Raphael Warnock, to prevail in order to snatch the Senate from the Republicans. Outgoing President Donald Trump's party needs either Kelly Loeffler or David Perdue to hold their seat to preserve its majority.

Donald Trump
US President Donald Trump campaigned in Georgia for Senate Republicans Kelly Loeffler (pictured) and David Purdue on the eve of their critical runoff elections on January 5, 2021 that will determine the balance of power in the US Senate Photo: AFP / SANDY HUFFAKER

US media declared both races too close to call following the close of polls at 7:00 pm (0000 GMT), and Georgia officials have said results may not be known until Wednesday or later.

"Georgia -- The nation is looking to you to lead us forward," tweeted President-elect Biden, who like Trump visited the Peach State to rally supporters on the eve of the vote.

Georgia election
Democratic candidates for US Senate Jon Ossoff (L) and Raphael Warnock (R) are seeking to oust Republican incumbents in runoff elections that will determine the balance of power in Congress Photo: AFP / JIM WATSON

"The power is in your hands," wrote the 78-year-old Democrat.

Georgia was voting during a week of high political tensions in the United States, with Trump desperately scheming to reverse his election loss.

On Wednesday, Vice President Mike Pence is to preside over a joint session of Congress to certify the Electoral College vote that confirmed Biden as the winner of the White House.

Trump, who refuses to concede, is planning to address a rally called in protest at the certification, and he urged Pence to "reject fraudulently chosen electors" -- a move the vice president has no legal authority to make.

Hundreds of Trump supporters wearing red "Make America Great Again" caps were already gathered in downtown Washington Tuesday amid a heavy police presence as shop owners, fearing unrest, boarded up windows.

Biden beat Trump in Georgia by nearly 12,000 votes in November, but the runoff odds are not in Democrats' favor: Republicans have won all eight statewide runoffs since 1992.

Democrats led the early voting in Georgia and nationwide in November, and the expectation is that they did so again in the runoffs, in which a record three million-plus people voted early amid the coronavirus pandemic.

Georgia elections
Graphic on the two runoff elections in Georgia on January 5 which will decide which party controls the US Senate. Photo: AFP / Jonathan WALTER

Voting figures show Republicans more than Democrats tend to prefer casting ballots in person on election day.

With the election on a knife edge, Robert Lowe, a 74-year-old retired improv comedian, called it "the most important election in my lifetime," after casting his ballot at an Atlanta church for the Democrats.

If Republicans retain control of the Senate there will be "continued obstruction" in Washington, Lowe told AFP.

Republicans hold 50 seats in the 100-seat Senate and a victory in just one of the runoff races would give them a majority and the ability to thwart Biden's agenda.

Ossoff, 33 and a documentary producer, is running against Perdue, a 71-year-old business executive who was elected to the Senate in 2014.

Warnock, a 51-year-old Black pastor, is taking on Loeffler, 50, a businesswoman appointed to the Senate in December 2019.

Trump's rally came a day after The Washington Post published a recording of a phone call in which the 74-year-old president pressured Georgia officials to reverse the certified vote of November's election and hand him victory in the state.

On the tape, Trump is heard telling Georgia Secretary of State Brad Raffensperger he wants to "find 11,780 votes" -- one more than Biden's margin of victory.

Certification of the Electoral College vote is usually just a formality but dozens of House Republicans and 12 Senate Republicans loyal to Trump have said they will raise objections on Wednesday.

The move is doomed to fail, as they are far short of the votes needed to block final validation of the vote.

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