Democrats closed in on control of the U.S. Senate early Wednesday with a stunning come-from-behind victory in one of Georgia's twin runoff elections and the lead in the second contest, races that could reshape the first two years of President-elect Joe Biden's term by giving Democrats a clearer path to enacting their legislative priorities.

After swapping leads over the course of the night Tuesday, Democrats Raphael Warnock and Jon Ossoff benefited from late counts in Democratic areas of the state, which gave Warnock an increasing lead over Republican Sen. Kelly Loeffler as the final precincts were counted. Edison Research called the race for Warnock early Wednesday.

Ossoff held a narrower lead over David Perdue (R), whose Senate term expired Sunday. Most of the remaining ballots were believed to be from strongly Democratic areas.

The Warnock win — and the possibility of a second Democratic victory — represented a historic upset in a longtime Republican bastion, signaling a clear shift in the political makeup of the state that Biden won nine weeks ago. Warnock will be the first African American Democratic senator from a former Confederate state, and Ossoff, 33, would be the youngest newly elected Democratic senator since Biden in 1973.

The races also represented a forceful rejection of President Trump in the final days of his term, and they raised questions about the central role the president has vowed to maintain in his party after his departure from office.

At stake in Tuesday’s contests was the governing coalition Biden will enjoy in his first years in office. If both Democrats win, they would flip control of the Senate, with the tie-breaking vote of Vice President-elect Kamala D. Harris, opening the door for potential passage of legislation Democrats campaigned on over the past two years, including­ an expansion of federal health-care subsidies, a tax increase on the wealthy and a comprehensive immigration overhaul.