A growing number of Democrats are calling on Joe Biden to end his presidential re-election bid and step aside for a younger contender.

Concerns over his poor debate performance have spread over the past fortnight among politicians, donors and others within the party.

The 81-year-old has defiantly declared he is “not going anywhere”.

But the pressure is mounting as he continues to lose ground in the polls against Republican rival Donald Trump.

It began five days after the June 27 debate with Lloyd Doggett, a 15-term Texas congressman, who said that it was time for Mr Biden to “make the painful and difficult decision to withdraw”.

Mr Doggett, 77, who sits on the powerful House Ways and Means Committee, said he respected “all that President Biden has achieved” but that the Democrat had failed to “effectively defend his many accomplishments” on the debate stage.

He has since been joined by other House of Representatives colleagues:

• Arizona left-winger Raul Grijalva told The New York Times that the campaign was in a “precarious” state and Mr Biden had to now “shoulder the responsibility” of holding the White House.
• Seth Moulton of Massachusetts and a 2020 presidential candidate, told WBUR that he no longer had confidence that Mr Biden could beat Trump.
• Mike Quigley, an Illinois congressman involved in planning the party convention, made a direct plea to the president on MSNBC, saying that his “legacy is set” but it was time to “let someone else do this”.
• Angie Craig, a Minnesota Democrat representing a swing district, fretted over Mr Biden’s debate performance and his “lack of a forceful response” since then, and warned “there is only a small window left” to choose a replacement.
• Adam Smith of Washington, the top Democrat on the House Armed Services Committee, said Mr Biden could no longer “clearly, articulately, and strongly make his case to the American people”.
• Mikie Sherrill, a centre-left New Jersey congresswoman, wrote that “the stakes are too high – and the threat is too real – to stay silent” because Democrats “cannot allow Trump to return to the White House”.
• Pat Ryan, from a vulnerable seat in the state of New York, urged Mr Biden “to deliver on his promise to be a bridge to a new generation of leaders” and step aside “for the good of our country”.
• Long-time Oregon leftist Earl Blumenauer, who is retiring at the end of this term, said he hoped Mr Biden would end his bid because the 2024 race was “not just about extending his presidency but protecting democracy”.
• Hillary Scholten, from a Michigan swing district, told The Detroit News: “We just have too much at stake in this election to sit on the sidelines and be silent while we still have time to do something.”

It took just under two weeks from the debate for the first Democrat senator to call for Mr Biden to drop out. Peter Welch, of Vermont, told the Washington Post: “We need him to put us first, as he has done before,” he said. “I urge him to do it now.”

Other prominent figures have also joined the growing chorus:

• New York Lieutenant Governor Antonio Delgado, a former member of the House of Representatives, said Mr Biden “can add to his legacy, showing his strength and grace, by ending his campaign”.
• Ex-Ohio congressman Tim Ryan, former housing secretary Julian Castro and self-help guru Marianne Williamson – all former primary opponents of Mr Biden – have called on him to withdraw.
• George Clooney, the Hollywood actor and major party fundraiser, said in The New York Times that Mr Biden could not beat time. His article was titled: “I Love Joe Biden. But We Need a New Nominee.”

Senior Democrats, including party leaders in Washington, have held their fire and straddled the fence on whether Mr Biden should continue his 2024 bid.

Nancy Pelosi, the former House speaker, declined to directly answer whether she wanted him to keep running. She did so on MSNBC’s Morning Joe, the president’s favourite news programme.

“I want him to do whatever he decides to do,” she said, adding that “time is running short” for him to make that call.

Her replacement as House Democratic chief, Hakeem Jeffries, has so far not commented. CBS News, the BBC’s US partner, has reported he is expected to soon convey the growing concerns of his caucus directly to the president.

Senate Majority Leader Chuck Schumer has publicly said he is “for Joe” but, per Axios, is privately signalling to donors that he is open to replacing Mr Biden.

Many politicians have carefully parsed their words, expressing respect for the president’s accomplishments in office while noting that his poor polling and concerning public appearances raise significant questions.

Montana’s Jon Tester and Ohio’s Sherrod Brown are two of the most vulnerable senators up for re-election. While Mr Brown has largely dodged questions on the topic, Mr Tester says Mr Biden “has got to prove” that he is up to the job.

Colleagues have echoed those concerns. Patty Murray, of Washington state, said Mr Biden “must do more to demonstrate he can campaign strong enough to beat Donald Trump”. Michael Bennet, of Colorado, warned that Mr Trump was on track to win “by a landslide, and take with him the Senate and the House”.

Two high-profile House members, California’s Adam Schiff and Maryland’s Jamie Raskin, as well as Massachusetts Governor Maura Healey, have also publicly aired their doubts since the 27 June debate.

But the president is not without his backers.

Vice-President Kamala Harris has not wavered in standing by her boss, as have potential replacement candidates such as Gavin Newsom, California’s governor, and his Michigan and Maryland contemporaries Gretchen Whitmer and Wes Moore.

Also standing by Mr Biden, and enthusiastically so, are outspoken figures on the Hill such as Alexandria Ocasio-Cortez, a New York congresswoman, and John Fetterman, a Pennsylvania senator.