Raphael Warnock will become the first black senator to represent the US state of Georgia in its history, claiming victory in one of two crucial Senate run-offs.
The Associated Press has called one race for the Democratic candidate, who currently leads his Republican opponent Kelly Loeffler by 50.5-49.5, with 97 per cent of the votes counted.
The Democratic Party is now within reach of controlling the US Senate, with the results of one more race to determine whether it can control all of Congress.
That race remains underway and tightly-contested early on Wednesday local time. Republican candidate David Perdue and Democratic candidate Jon Ossoff are tied at 50-50, with 97 per cent of the vote counted and Mr Ossoff leading by around 3,500 votes.
Most of the remaining votes are in Democrat-leaning areas.
The Republicans currently hold 50 seats in the Senate, while the Democrats have 48. If Mr Perdue wins his race, the Republican party will retain control of the chamber.
However, if Mr Ossoff wins, the Senate will split 50-50, giving incoming vice president Kamala Harris the tie-breaking vote and effectively handing the Democrats complete control of the federal government.
The Democrats must win both Georgia races to seize Senate control from the Republicans. Failure to do so would make it much more difficult for incoming President Joe Biden to enact new legislation in a bitterly divided Congress.
The results could be known by Wednesday local time, Georgia Secretary of State Brad Raffensperger told CNN, although the outcome may remain in doubt for days if the margins are razor-thin.
Officials were set to begin counting ballots as soon as polls closed at 7pm local time (11am AEDT), although a handful of sites will stay open later after earlier delays.
The final days of the tense contests, which set records for campaign spending and early turnout in Georgia, were dominated by Mr Trump’s continued efforts to subvert the presidential election results.
On Saturday, Mr Trump pressured Georgia Secretary of State Brad Raffensperger, a fellow Republican, to “find” enough votes to reverse Mr Biden’s victory, again falsely claiming massive fraud.
Mr Trump’s efforts to undo his loss – with some Republicans planning to object to the certification of Mr Biden’s win when Congress meets on 6 January to formally count the presidential vote – have caused a split in his party and condemnation from critics who accuse him of undermining democracy.
Mr Biden, due to take office on 20 January, was the first Democratic presidential candidate to win in Georgia since 1992.
Mr Trump and Mr Biden campaigned in Georgia on Monday. It remains to be seen whether Mr Trump’s claims about election fraud will dissuade Republicans from voting in Georgia, as some in the party have feared.
Democrats control the House of Representatives, with the number of seats allotted to states determined by their population. Democratic control of both chambers could boost Mr Biden’s legislative agenda in areas such as economic relief amid the coronavirus pandemic, climate change policy, healthcare and policing reform.
– Additional reporting by AFP.
