US President Joe Biden told Americans in a televised speech that it was time to “pass the torch to a new generation” as he sought to explain the historic decision to end his faltering re-election campaign.
Biden, 81, said he was withdrawing from his candidacy and supporting Vice President Kamala Harris to unite fellow Democrats and the country.
The White House speech was his first public appearance since withdrawing from the race on July 21, paving the way for Ms. Harris to run for the party nomination.
Meanwhile, Republican presidential candidate Donald Trump said at a rally that Ms Harris was a “radical left-wing lunatic”.
Polling so far suggests the former president and Ms. Harris are neck-and-neck in a hypothetical race.
During Wednesday night’s remarks, Biden spoke for 11 minutes in the Oval Office, with his wife Jill, son Hunter and daughter Ashley in the room, as well as some key White House staff.
“I respect this office,” he said. “But I love my country more.”
“I decided the best way forward was to pass the torch to a new generation,” added Mr. Biden, who has served in public office for more than half a century. “This is the best way to unite our country.”
The president vowed to “get the job done for the American people” before his term ends in January, calling Ms Harris, 59, an “experienced, tough and capable” partner.
Biden said he believes his record warrants re-election. But “nothing can stand in the way of saving our democracy,” he continued. “This includes personal ambition.”
“That’s the great thing about America, kings and dictators don’t rule. The people rule. History is in your hands. Power is in your hands. The idea of America is in your hands.”
The White House press corps heard applause from family members and staff as they were led out of the room, and the president spoke softly.
Biden made no mention of the growing pressure he has faced for three weeks from top Democrats and donors to step down after a poor performance in a debate with Trump late last month.
Trump, 78, posted on his social media platform Truth Social on Wednesday night that the president was “almost incomprehensible and terrible!”
Earlier in the day, the Republican, speaking at a rally in Charlotte, North Carolina, attacked both Ms. Harris and Mr. Biden, whom he called the most destructive president in American history.
“For three and a half years, lying Kamala Harris has been the ultra-liberal driving force behind every Biden disaster,” he said.
“She is a radical left-wing lunatic who will destroy our country if she gets a chance in office.”
At a White House press briefing earlier in the day, press secretary Karine Jean-Pierre said Mr. Biden’s withdrawal had “nothing to do with his health” but declined to give further details.
She also denied to reporters any “cover-up” of Mr Biden’s cognitive abilities.
Ms. Harris is campaigning.
Earlier Wednesday, she spoke at the historically black Zeta Phi Beta sorority in Indianapolis, telling members her new campaign was “no joke” and asking for their help getting elected.
“At this moment, I believe we face a choice between two different visions for our country, one that looks to the future and one that looks to the past,” she said. “With your support, I am working on fight for the future of our country.”
She will be the first Black, South Asian American and female president, although she will need Black voters to turn out in November.
However, activist group Black Lives Matter said in a statement on Tuesday that Democrats had “manipulated black voters” by appointing Ms. Harris at the behest of billionaire donors and had a “blatant disregard for democratic principles.”
Biden is the first sitting president not to seek re-election since 1968, when Lyndon Johnson halted his campaign amid declining support during the Vietnam War.
Some Republicans have called on Biden to resign immediately as president, arguing he can’t run the country if he can’t run for office – a charge the White House has rejected.
On Thursday, Biden is expected to meet with Israeli Prime Minister Benjamin Netanyahu at the White House and meet with the families of American hostages still being held in Gaza.
