dpa

Washington

US President Joe Biden announced on Sunday that he is withdrawing from the race to be president for a second term, a historic decision that throws the Democratic Party into upheaval as Republican rival Donald Trump’s campaign gains steam.

Biden said that Vice President Kamala Harris had his "full support” to replace him on the ballot in November’s election. He also said that he will finish out the remainder of his term, which ends in January.

But with the party’s presumptive nominee now gone and just over 100 days to go, the clock is ticking for Democrats to begin the fraught process of replacing him and launching a viable campaign to take on Trump.

It was not immediately clear if the party would quickly join together around Harris, or whether other candidates would scramble to put themselves forward and be anointed Biden’s replacement.

Biden’s decision sent shock waves across the country - and globe - and came after massive pressure from within his own party not to put himself forward as the official nominee.

"It has been the greatest honor of my life to serve as your president. And while it has been my intention to seek re-election 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 in a letter posted on his personal X account.

A television debate performance against his rival Donald Trump at the end of June, during which 81-year-old Biden struggled several times to give coherent answers or challenge falsehoods uttered by Trump, prompted nationwide concern about whether he was still mentally fit for office.

The issue of Biden’s age has since dominated the US election campaign, overshadowed a NATO summit, and been used repeatedly Trump, 78, to attack his opponent.

Until now, Biden had insisted that he would run as the Democratic candidate in the November 5 election and that he was fit for office, at one point saying that "only the Almighty” could make him drop out of the race.

But there have a been series of high-profile defections - including Senator Joe Manchin of West Virginia on Sunday - and influential figures voicing scepticism about the viability of Biden’s path to re-election, including the former speaker of the House of Representatives Nancy Pelosi.

In endorsing Harris, Biden wrote: "My very first decision as the party nominee in 2020 was to pick Kamala Harris as my vice president.

And it’s been the best decision I’ve made. Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year. Democrats - it’s time to come together and beat Trump. Let’s do this.”

Clintons back Harris

Former president Bill Clinton and former secretary of state Hillary Clinton have given Vice President Kamala Harris their endorsement to succeed Joe Biden as president.

"We are honored to join the President in endorsing Vice President Harris and will do whatever we can do to support her,” the Clintons said in a joint statement posted on social media, after Biden dropped out of the 2024 race and said he wanted his deputy to replace him.

"We join millions of Americans in thanking President Biden for all he has accomplished, standing up for America time and again, with his North Star always being what’s best for the country,” they said.

"We’ve lived through many ups and downs, but nothing has made us more worried for our country than the threat posed by a second [Donald] Trump term,” they continued.