The southern US state of Georgia is holding critical run-off elections that will determine which political party controls the country’s Senate.
Two Senate seats, both currently held by Republicans, are up for grabs in the tightly contested races on Tuesday.
The outcome will impact how easily Democratic president-elect Joe Biden can implement his agenda.
The run-off is being held because no candidate succeeded in garnering the 50 per cent of the vote needed to win the election that was held in November.
The top two contenders from each race are now facing off.
In one of the races, incumbent Republican candidate David Perdue, 70, is up against the much younger Democratic candidate Jon Ossoff, the 33-year-old former head of a documentary film company.
Ossoff spent five years working for a Democratic Congressman from the state capital Atlanta prior to working in media.
Perdue, a staunch ally of US President Donald Trump, has been in the Senate since 2015.
In the other race, Republican Senator Kelly Loeffler, 50, is running against the Reverend Raphael Warnock, a 51-year-old newcomer to politics.
Loeffler, who was appointed to the Senate in 2019 by Georgia’s governor after the previous senator resigned, is running to hold onto her seat.
Her Democratic opponent helped co-found the New Georgia Project, a voting rights organisation, and is a pastor for the church where civil rights leader Martin Luther King Jr preached.
If Republicans win just one of the two races, they will maintain control of the upper chamber of Congress.
If the Democrats win both the Senate will be split but the vice president, which in the new administration will be Democrat Kamala Harris, can act as a tie breaker.
Democrats control the lower chamber, the House of Representatives.
With the balance of power in Washington DC up for grabs, both Biden and Trump descended on the state to rally their sides.
Biden spoke at a rally in Atlanta, Georgia on Monday and urged voters to send Ossoff and Warnock to Congress, arguing that Perdue and Loeffler are more loyal to Trump than they are to the people of Georgia.
“By electing John and the Reverend you’ll be sending a powerful message to Congress and to the country, that’s it’s time for this nation to finally come together,” Biden said.
Trump held a rally in the town of Dalton.
Over the course of his 83-minute speech, the president continued to insist that he won the November election and repeated allegations of voter fraud in the state.
“They’re not going to take this White House. We’re going to fight like hell, I’ll tell you right now,” he said.
A showdown is expected in Congress on Wednesday when lawmakers from both houses meet to count and certify the states’ Electoral College vote totals, the final step on Biden’s path to being sworn in as the 46th president on January 20.
A group of Republican Trump loyalists has vowed to try and block the formal certification of the results at Wednesday’s joint session of Congress.
The plan is all but certain to prove futile even if it prolongs the process.
Initial results in Georgia’s elections are expected shortly after polls close at 7pm local time but it could take several days to know the winners if the races prove as tight as surveys suggest.