President Joe Biden's reelection bid faced fresh turmoil after reports that top Democratic leaders had privately pushed him to end his campaign, while Donald Trump was set to accept the Republican presidential nomination on Thursday.

U.S. Senate Majority Leader Chuck Schumer, House Minority Leader Hakeem Jeffries and former House Speaker Nancy Pelosi have all expressed deep concerns directly to Biden in recent days that he will not only lose the White House but also cost the party any chance of winning back the House of Representatives in the Nov. 5 election, according to reports in multiple news outlets.

His troubles were compounded on Wednesday when he tested positive for COVID-19 during a campaign visit to Nevada, forcing him to return to his Delaware home to work in isolation.

His campaign is now pursuing a razor-thin path to reelection, with four of the seven most competitive states now looking increasingly out of reach.

So far, only 20 out of 264 Democrats in Congress have called on Biden, 81, to drop out following his poor June debate performance against Trump, 78, which raised questions about Biden's ability to win and to carry on in a high-pressure job for another four years if he were to succeed.

Representative Adam Schiff, a senior House lawmaker running for a Senate seat in California, became the latest Democrat to call on Biden to bow out on Wednesday.

White House officials believe Schiff was backed by Pelosi, according to a White House source speaking on condition of anonymity. That could be an ominous sign for Biden, as the former House speaker is still one of the most influential Democrats in Washington. "Nancy is all over this. She doesn't miss," the White House source said.

Some lawmakers think Biden now may be more open to stepping aside. "He's done what's best for America ... I think he'll keep doing so," Democratic U.S. Senator John Hickenlooper told Reuters. "He's working towards that."

Hickenlooper declined to say whether he believed Biden should step aside as a candidate.

REPUBLICAN UNITY

Meanwhile, Trump will cap the four-day Republican National Convention in Milwaukee with his first public address since he survived an assassination attempt in Pennsylvania on Saturday, in which a bullet grazed his ear.

Campaign staffers say the experience has prompted him to revise his acceptance speech to emphasize inclusiveness, rather than attacks on Biden's Democrats.

Viewers "may see a bit of a different version of Trump tonight, perhaps a softer version," Trump's daughter-in-law Lara Trump said on CBS on Thursday.

"I don’t think you can go through what he went through on Saturday, really a near-death experience, and not come out on the other side impacted," said Lara Trump, who serves as Republican National Committee co-chair. Trump is due to speak at around 10 pm ET (0200 GMT, Friday).

The convention has put Republican unity on display, in contrast to the divisions roiling Democrats, with former rivals including Florida Governor Ron DeSantis and former South Carolina Governor Nikki Haley offering strong endorsements of his candidacy.

Senator J.D. Vance, Trump's running mate and another former critic-turned-loyalist, presented himself on Wednesday as the son of a neglected industrial Ohio town who will fight for the working class if elected in November.

As he chronicled his hardscrabble journey from a difficult childhood to the U.S. Marines, Yale Law School, venture capitalism and the U.S. Senate, Vance, 39, said he understood working Americans' struggles.

"I grew up in Middletown, Ohio, a small town where people spoke their minds, built with their hands and loved their God, their family, their community and their country with their whole hearts," Vance said. "But it was also a place that had been cast aside and forgotten by America's ruling class in Washington."

As the first millennial on a major party ticket, Vance, who has embraced Trump's mixture of conservative populism and isolationist foreign policy, is well positioned to be the future leader of Trump's Make America Great Again movement.

In his speech, he appealed to the working and middle classes in Michigan, Pennsylvania and Wisconsin specifically - three Rust Belt swing states likely to decide the election. The Biden campaign sees those states critical if Democrats are to win in November.

Vance has opposed military aid for Ukraine and defended Trump's attempts to overturn his 2020 election loss to Biden.

For Trump's political opponents, his hold on the party portends a darker moment in which he follows through on his promises to expand the power of the presidency, exact revenge on his enemies and threaten longstanding democratic institutions.

Vance would advance "an agenda that puts extremism and the ultra wealthy over our democracy," the Biden campaign said on Wednesday.