President Joe Biden vowed on Friday to continue his campaign for reelection even as more fellow Democrats in Congress urged him to end his floundering campaign, fearing that it could cost the party dearly in the Nov. 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 COVID -- 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 this 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, 32 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.

Democrats are increasingly worried about a Republican sweep in the Nov. 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.

"Your candidacy is on a trajectory to lose the White House and potentially impact crucial House and Senate races down ballot. It is for these reasons that I urge you to step aside," wrote Representative Zoe Lofgren, one of at least nine Democratic lawmakers to call on Biden to drop out on Friday.

Lofgren is a close ally of former House Speaker Nancy Pelosi, one of the most influential Democrats. Pelosi has not publicly called on Biden to drop out but has privately told him he cannot win, according to a White House source speaking on condition of anonymity.

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.

A Democratic group called Pass the Torch said it would run TV ads on MSNBC's "Morning Joe," one of Biden's favorite shows, urging him to drop out.

'A lot of work to do'

Biden campaign chairwoman Jen O'Malley Dillon acknowledged that Biden faces a difficult path to reelection 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 on MSNBC.

Though a Reuters/Ipsos poll earlier this week found Biden and Trump effectively tied nationally, 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.

Harris will address a group of donors on short notice on Friday afternoon, at the request of Biden senior advisers, according to a source familiar with the situation.

Democrats could face some limits on what they can do with the $91 million Biden's campaign had on hand as of the end of last month if he were to drop out, according to campaign finance experts.

Trump tightens grip on Republicans

Trump on Thursday night delivered a dramatic account of the attempt on his life by a gunman at a Pennsylvania rally last Saturday and sought to appeal to undecided voters and said he would be a president for "all of America, not half of America."

But he spent much of the rest of his meandering 92-minute acceptance speech repeating well-worn attacks on the Biden administration and attacking migrants, a theme that has always animated his presidential campaigns.

He claimed without evidence that his criminal indictments were part of a Democratic conspiracy, predicted Biden would usher in "World War Three" and described what he called an "invasion" of migrants over the southern border.

Trump and his 39-year-old running mate, U.S. Senator J.D. Vance, are due to campaign on Saturday in Michigan, one of three Rust Belt states seen as must-wins for Biden's campaign.