ATLANTA, Jan. 6 (Reuters) — Democrats won one U.S. Senate race in Georgia and led in another on Wednesday, moving closer to a surprise sweep in a former Republican stronghold that would give them control of Congress and the power to advance President-elect Joe Biden's agenda.

Raphael Warnock, a Baptist preacher from the historic church of Martin Luther King Jr., beat Republican incumbent Kelly Loeffler to become the first Black senator in the deep South state's history.

Jon Ossoff, a documentary filmmaker who at 33 would become the Senate's youngest member, also declared victory with a narrow lead over incumbent David Perdue, although media had yet to declare a winner in that race.

If upheld, the results would amount to a final defeat for outgoing President Donald Trump, who stands to be the first U.S. president since 1932 to lose the White House and both chambers of Congress in a single term.

Trump held rallies for both Republican candidates, but overshadowed the campaign with false accusations that his own loss in the November presidential election was tainted by fraud, repeatedly attacking Republican officials in the state.

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With 98% of the vote counted, Warnock was ahead of Loeffler by 1.2 percentage points, roughly 54,000 votes, according to Edison Research. Ossoff led Perdue by more than 17,000 votes, just shy of a 0.5 percent threshold to avoid a recount. Most outstanding votes were from Democratic-leaning areas.

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Winning both contests would give Democrats control of the Senate, creating a 50-50 split and giving Vice President-elect Kamala Harris the tie-breaking vote once she and Biden take office on Jan. 20. The party already has a narrow majority in the U.S. House of Representatives.

Republicans would retain control of the Senate if they held on to at least one of the seats. That would allow them to block Biden's political and judicial appointees, as well as his legislative priorities from coronavirus relief to climate change.

The campaign's final days were overshadowed by Trump's attempts to pressure Republican Georgia officials to "find" enough votes to overturn Biden's victory in the state.

On Trump's shoulders

If Democrats won, the losses would "fall squarely on the shoulders of President Trump and his actions since Nov. 3," Gabriel Sterling, a Republican and a top election official in the state, told CNN.

The election signaled a shift in the politics of Georgia and the wider deep South. At least 4.5 million voters participated, smashing earlier turnout figures for runoff races. Democrats have worked hard to increase turnout among Black voters, their most reliable supporters in the region.

In a video message, Warnock, whose Ebenezer Baptist Church is legendary in Georgia because of its role in the civil rights movement under King, recalled his humble upbringing as one of 12 children of a woman who worked in cotton fields.

"Because this is America, the 82-year-old hands that used to pick somebody else's cotton went to the polls and picked her youngest son to be a United States senator," he said.

Declaring victory, Ossoff said he looked forward "to serving you in the United States Senate with integrity, with humility, with honor."

Both Republican senators, following the lead of Trump who has never conceded his own loss, predicted they would ultimately win and insisted they would fight on: "We have a path to victory and we're staying on it," Loeffler told supporters in Atlanta.

Republican U.S. Senator Kelly Loeffler speaks at the GA GOP election night event for the run-off election for Georgia’s two Senate seats in Atlanta, Georgia, on Jan. 6. REUTERS/Brian Snyder
Republican U.S. Senator Kelly Loeffler speaks at the GA GOP election night event for the run-off election for Georgia’s two Senate seats in Atlanta, Georgia, on Jan. 6. REUTERS/Brian Snyder

During the campaign, Republicans had painted Ossoff and Warnock as radicals who would pursue a hard-left agenda. But that message failed to resonate with many white suburbanites who have increasingly abandoned the Republican party under Trump.

Trump's flailing efforts to overturn his own defeat move to Congress later on Wednesday, when Vice President Mike Pence is due to preside over the counting of electoral votes to certify Biden's victory.

Trump has called on Pence to throw out the results in states he narrowly lost, although Pence has no authority to do so. Some Republican lawmakers have said they will try to reject some state tallies, a move that stands no chance of success but which could force debate and drag out the certification process.

Trump's supporters plan to rally in the streets of Washington, with the city bracing for potential violence. Police banned the leader of a far-right group from the city and made several arrests as protests ramped up on Tuesday. Trump is due to address the crowd at 11 a.m.

(Reporting by Nathan Layne and Rich McKay in Atlanta; Additional reporting by Jason Lange, Susan Heavey and Andy Sullivan; Writing by Andy Sulliva and John Whitesides Editing by Soyoung Kim and Peter Graff)