Close contests unfolded on Tuesday in two US Senate races in Georgia that will decide which party controls the chamber, Reuters reports.

Republican incumbents David Perdue and Kelly Loeffler faced Democratic challengers Jon Ossoff and Rev. Raphael Warnock in the runoff election on Tuesday.

As of 12:50 a.m. EST on Wednesdau, Loeffler trailed Warnock 49.59% to 50.41%, while Perdue held a razor-thin lead over Ossoff with 2,190,203 votes to Ossoff's 2,189,284, or 50.01% to 49.99%.

Top Georgia election official Gabriel Sterling said on Tuesday evening that military and overseas ballots postmarked on Tuesday will be accepted through Friday, potentially delaying the final vote counts until then.

An Edison exit poll of more than 5,200 voters found half had voted for President Donald Trump in November and half for Joe Biden. The voters were also evenly split on whether Democrats or Republicans should control the Senate.

Democrats must win both contests in Georgia to take control of the Senate. This would create a 50-50 split in the Senate, giving Vice President-elect Kamala Harris the tie-breaking vote after she and Biden take office on January 20.

If Republicans hold onto the Senate, they would effectively wield veto power over Biden’s political and judicial appointees as well as many of his policy initiatives in areas such as economic relief, climate change, healthcare and criminal justice.

The results could be known by Wednesday, Georgia Secretary of State Brad Raffensperger told CNN.

Both Biden and Trump held rallies in Georgia on Monday, in which they encouraged voters to take part in Tuesday’s vote.

Biden, in his speech, accused Perdue and Loeffler of putting their loyalty to Trump ahead of the people of Georgia.

He accused the two of enabling Trump’s efforts to overturn the election, saying, “You have two senators who think their loyalty is to Trump, not to Georgia, who think they swore an oath to Donald Trump and not the US constitution.”

Trump, who held a rally of his own later in the evening, focused the first part of his speech on the November presidential election and said, "There's no way we lost Georgia. I had two elections. I won both of them.”

"The radical Democrats are trying to capture Georgia Senate seats, so they will have absolute power over every aspect of your lives, if the liberal Democrats take the Senate and the White House. And they are not taking this White House. We will fight like hell. I will tell you right now," stressed Trump.

If elected, Warnock would become Georgia’s first Black US senator and Ossoff, who is Jewish, would become the Senate’s youngest member at 33 years of age.

Warnock has come under fire for controversial remarks related to Israel that he made in a 2018 sermon at his church, when he asserted that Israel "shoots unarmed Palestinians".

He walked back those remarks last month, saying he had an “increasing recognition” of the danger that Hamas poses to Israel since his harsh criticisms of Israel in that sermon. Warnock also said he opposed the anti-Israel Boycott, Divestment and Sanctions (BDS) movement.