US President Joe Biden abandoned his reelection bid on Sunday under growing pressure from his fellow Democrats and endorsed Vice President Kamala Harris as the party’s candidate to face Republican Donald Trump in the November election.

Biden, who at 81 is the oldest person ever to have occupied the Oval Office, said he would remain in the presidency until his term ended on January 20, 2025, and would address the nation this week.

Biden, who has not been seen in public since testing positive for Covid-19 last week, was isolating at his home in Rehoboth Beach, Delaware.

“While it has been my intention to seek reelection, I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as President for the remainder of my term,” Biden wrote on X.

The move dramatically reshapes a White House contest that has been shaken repeatedly in the last month. Biden’s disastrous June 27 debate performance drove his fellow Democrats to urge him to drop out. Then on July 13, a gunman attempted to assassinate former President Trump, 78. And last week Trump named hardline Republican US Senator JD Vance, 39, to serve as his vice presidential running mate.

In opinion polls, Americans had expressed widespread dissatisfaction with a potential Biden-Trump rematch. Shortly after Biden’s announcement, Trump told CNN: “Harris will be easier to beat than Joe Biden would have been.”

Democratic National Committee Chair Jaime Harrison said the American people would soon hear from the party on next steps and the path forward for the nomination process. It was the first time in more than a half-century that an incumbent US president gave up his party’s nomination.

If Harris, 59, emerges as the nominee, she would become the first Black woman to lead a major-party ticket in US history. A former attorney general of California and former US senator, she ran unsuccessfully for president against Biden in 2020.

“My intention is to earn and win this nomination,” Harris said in a statement. “I will do everything in my power to unite the Democratic Party—and unite our nation—to defeat Donald Trump.”

Harris campaign officials, allies and supporters have started making calls to secure the support of delegates for her nomination ahead of the Democratic National Convention in Chicago from August 19-22, multiple sources said.

Democratic state party chairs held a Sunday afternoon call to discuss backing Harris as the party’s nominee. Several participants said Harris has the full support of the chairs.

Opposition to Biden’s campaign from within his party gained steam over the past week with 36 congressional Democrats—more than one in eight—publicly calling on him to drop out, driven by concerns over his mental acuity.

Lawmakers said they feared he could cost them not only the White House but also the chance to control either chamber of Congress next year, which would leave Democrats with no meaningful grasp on power in Washington.

That stood in sharp contrast to what played out in Milwaukee last week, when Republican convention delegates united around Trump, whose refusal to acknowledge his 2020 loss to Biden sparked a January 6, 2021, assault on the US Capitol.

It was unclear whether other senior Democrats would challenge Harris for the nomination—she was widely seen as the pick of many party officials—or whether the party itself would choose to open the field for nominations.

Governor Gavin Newsom of California, who had been mentioned as a possible replacement for Biden at the top of the ticket, threw his support behind Harris.

“With our democracy at stake and our future on the line, no one is better to prosecute the case against Donald Trump’s dark vision and guide our country in a healthier direction than America’s Vice President, @KamalaHarris,” Newsom wrote on X.

Two other potential challengers, Governor Gretchen Whitmer of Michigan and Governor Andy Beshear of Kentucky, issued statements praising Biden but did not mention the vice president.

Pennsylvania Governor Josh Shapiro and Transportation Secretary Pete Buttigieg on Sunday issued statements backing Harris’ bid. Both are among a handful of Democrats seen as potential vice presidential material.

LAST-MINUTE SHIFT

As of Saturday night, Biden was telling allies that he planned to stay in the race, but changed his mind on Sunday afternoon, a source familiar with the matter said.

“At around 1:45 pm today, the president told his senior team that he had changed his mind,” the source told Reuters, speaking on condition of anonymity. Biden announced his decision on social media within minutes after that.

Polling shows that Harris performs no better statistically than Biden against Trump.

In a hypothetical head-to-head match-up, Harris and Trump were tied with 44% support each in a July 15-16 Reuters/Ipsos poll conducted immediately after the July 13 assassination attempt on Trump. Trump led Biden 43% to 41% in that same poll, though the 2 percentage point difference was not meaningful considering the poll’s 3-point margin of error.

Congressional Republicans argued on Sunday that Biden should resign the office immediately, which would turn the White House over to Harris and put House of Representatives Speaker Mike Johnson, a Republican, next in line in succession.

“If he’s incapable of running for president, how is he capable of governing right now? I mean, there is five months left in this administration. It’s a real concern, and it’s a danger to the country,” Johnson told CNN on Sunday before Biden’s announcement.

Biden’s campaign had $95 million on hand at the end of June, according to a Saturday filing with the Federal Election Commission. Campaign finance law experts disagree on how readily that money could be shifted to a Harris-led campaign.

Small-dollar donors raised over $27.5 million on ActBlue in the first five hours of Harris’ presidential campaign, the fundraising platform said on X.

FIRST SINCE LBJ

Biden’s historic withdrawal—he is the first sitting president to give up his party’s nomination for reelection since President Lyndon B Johnson during the Vietnam War in March 1968—leaves his replacement with less than four months to wage a campaign.

Biden was the oldest US president ever elected when he beat Trump in 2020. During that campaign, Biden described himself as a bridge to the next generation. Some interpreted that to mean he would serve one term, a transitional figure who beat Trump and brought his party back to power.

But he set his sights on a second term in the belief that he was the only Democrat who could beat Trump again. In recent weeks, his advanced age became more apparent. His gait became stilted and a childhood stutter occasionally returned.

Calls for Biden to reconsider his candidacy grew much louder after his shaky, halting performance during a first debate with Trump on June 27, giving pause to even some of his biggest supporters.

Donors began to revolt and supporters of Harris began to coalesce around her. Top Democrats, including former House of Representatives Speaker Nancy Pelosi, a longtime ally, told Biden he cannot win the election.

Harris is a former prosecutor, and Trump, two decades her senior, faces two outstanding criminal prosecutions related to his attempts to overturn the 2020 election result.

The former president is due to be sentenced in New York in September, having been convicted of trying to cover up a hush-money payment to a pornographic movie star. He has pleaded not guilty to all charges and claims all are politically motivated attempts to block him from returning to power.

Earlier this year, facing little opposition, Biden easily won the Democratic primary race to pick its presidential candidate, despite voter concerns about his age and health.

His staunch support for Israel’s military campaign in Gaza eroded support among some in his own party, particularly young, more liberal Democrats and voters of colour.

Many Black voters say Biden has not done enough for them, and enthusiasm among Democrats overall for a second Biden term had been low. Even before the debate with Trump, Biden was trailing the Republicans in some national polls and in the battleground states, he would need to win to prevail on November 5.