The most senior Republican in the US Senate has congratulated Democratic President-elect Joe Biden and Vice President-elect Kamala Harris on their election victories.
The move by Senate Majority Leader Mitch McConnell ends his long silence on the outcome of the presidential race.
In remarks on the Senate floor, Mr McConnell acknowledged the Democrats' win of the White House following yesterday's formal result issued by the Electoral College.
In a nearly 10-minute speech that mainly praised Republican President Donald Trump's tenure in office, Mr McConnell closed by saying: "Today I want to congratulate President-elect Joe Biden," adding that "he has devoted himself to public service for many years."
Mr McConnell, saying he had hoped for a "different result" in the 3 November election, also said, "All Americans can take pride that our nation has a female vice president-elect for the very first time."
Since early November, Mr McConnell has ignored pressure to acknowledge Mr Biden's victory, saying Mr Trump had the right to pursue legal challenges to the election outcome.
He steadfastly refused to refer to Mr Biden as president-elect.
Meanwhile, many of Mr McConnell's fellow Republicans have echoed Mr Trump's unfounded claims that the presidential election was stolen by domestic and foreign forces, including by tampering with electronic voting machines.
Over the past five weeks, some local elections officials have expressed fears that Mr Trump's rhetoric and that of some of his supporters could result in violence.
Yesterday, the Electoral College confirmed results that were apparent since 7 November that Mr Trump had no path to winning the election despite his repeated, unfounded claims of election fraud, which he reiterated yesterday.
Mr Trump's verbal and Twitter attacks, a flurry of mostly unsuccessful lawsuits and public rallies in which he spoke of an illegal election result raised fears that US democracy could suffer if enough Americans believed the president's accusations of fraud.
Senate Democratic Leader Chuck Schumer, in a speech following Mr McConnell's, urged Mr Trump to "end his term with a modicum of grace and dignity."
"For the sake of our democracy, for the sake of peaceful transition of power, he should stop the shenanigans, stop the misrepresentations and acknowledge that Joe Biden will be our next president," Mr Schumer said.
While Mr McConnell congratulated Mr Biden and Ms Harris, he made no mention of whether he would work in a cooperative manner with any of the new administration's initiatives following their swearing-in on 20 January.