President Joe Biden vowed on Friday to continue his campaign for re-election even as seven more fellow Democrats in Congress urged him to end his floundering campaign, fearing that it could cost the party dearly in the November 5 election.

More than one in 10 congressional Democrats have now publicly called on the 81-year-old incumbent – who is isolating at his Delaware home with a case of the coronavirus (Covid-19) – to drop out following a disastrous June debate against Republican Donald Trump that raised questions about Biden’s ability to win or to carry out his duties for another four years.

Biden remained defiant, saying he would resume campaigning soon.

“I look forward to getting back on the campaign trail next week to continue exposing the threat of Donald Trump’s Project 2025 agenda while making the case for my own record and the vision that I have for America,” he said in a statement, referring to a policy plan developed by Trump’s conservative allies.

The divide among Democrats stood in sharp contrast to the scenes that played out his week at the Republican National Convention in Milwaukee, where former party rivals united around Trump, who accepted the Republican nomination in a rambling speech that featured his familiar mix of grievance and bombast.

So far, 30 of the 264 Democrats in Congress have openly called for Biden to end his campaign, while other senior Democratic leaders have pushed him behind the scenes to do so, according to sources and media reports.

“We must face the reality that widespread public concerns about your age and fitness are jeopardizing what should be a winning campaign,” Representatives Jared Huffman, Marc Veasey, Chuy Garcia and Marc Pocan wrote in a letter on Friday.

Three other Democratic lawmakers also separately called on Biden to drop out: Senator Martin Heinrich and Representatives Zoe Lofgren and Greg Landsman.

Democrats are increasingly worried about a Republican sweep in the November 5 election that could leave Trump and his allies not only in charge of the White House but also with majorities in both chambers of Congress.

Former House of Representatives Speaker Nancy Pelosi is among those who have told Biden he cannot win in November, according to a White House source familiar with the matter.

After weeks of insisting he will remain in the race, sources say Biden is now taking calls to step aside seriously, and multiple Democratic officials think an exit is a matter of time.

Reports sourced to anonymous sources swirled in US media that Biden was making a plan for a dignified exit in the coming days, accepting warnings from senior Democrats that his time was up.

However, his campaign also pushed back, saying that while there had been some “slippage” in support, he was still the best candidate.

“Absolutely the president’s in this race,” campaign chairwoman Jen O’Malley Dillon told MSNBC’s Morning Joe programme. “Joe Biden is more committed than ever to beat Donald Trump.”

Dillon acknowledged that Biden faces a difficult path to re-election but said his support has not fallen significantly in recent weeks.

“We have a lot of work to do to make sure that we are reassuring the American people that, yes, he’s old, but he can do the job and he can win,” she said.

Though a Reuters/Ipsos poll earlier this week found Biden and Trump effectively tied, strategists from both parties say Biden’s path to victory is narrowing as he trails in most of the battleground states that will decide the election.

Were Biden to step aside as a candidate, Vice-President Kamala Harris, 59, could fill the role.

Reuters/Ipsos polling shows her as performing marginally better against Trump in a theoretical head-to-head matchup.