ATLANTA: Democrat Jon Ossoff on Wednesday claimed victory in the second of two Georgia run-off votes, claiming a win that would give President-elect Joe Biden control of the United States' Senate.

"Georgia, thank so much for the confidence you have placed in me. I am honored by your support, by your confidence, by your trust and I will look forward to serving you," Ossoff said in a televised statement.

The US media have not yet called the race, and Ossoff's Republican opponent David Perdue has not conceded.

In the other Georgia race, Raphael Warnock was projected to defeat Republican Kelly Loeffler, a 50-year-old businesswoman appointed to the Senate, the upper chamber of Congress, in December 2019.

Victory by both Democrats would be a major political upset in a state that has been reliably Republican for two decades, but which Biden won on November 3 as his way to victory against Trump in the presidential race.

It would also send reverberations through Washington, as it would hand Biden's Democrats the levers of power in the executive branch and both chambers of Congress.

Later 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 claims the election was fraudulent -- is planning to address a rally near the White House in protest at the certification, with his supporters gathering downtown amid a heavy police presence.

Dozens of House Republicans and 12 Senate Republicans have said they will raise objections to certification. The move lacks sufficient support and is set to fail.