Biden has repeatedly said he will not step down from the US presidential race, despite growing calls for him to do so, following the first debate against former President Donald Trump, who Biden defeated in 2020.
In the latest blow, Abigail Disney, granddaughter of Walt Disney, will halt donations to the Democrats until Biden removes himself as a candidate, the heiress told CNBC.
Vice President Kamala Harris is the leading contender to take his place in the November 5 election if Biden were to drop out, sources have said, though his allies believe he can assuage the concerns of voters and donors.
Biden was hosting the annual July 4 Independence Day festivities at the White House on Thursday, including a barbecue for a few thousand active-duty military service members and their families.
Reading from a teleprompter, Biden made no major errors in delivering brief remarks, but at one point appeared to go off script to make reference to a war cemetery that Trump declined to visit while in office.
He will give an interview to ABC News on Friday and travel to Wisconsin the same day for a campaign rally.
Dozens of Democrats in the House of Representatives are watching closely and prepared to ask Biden to step aside if he falters in the ABC interview, a source told Reuters. Democrats see capturing control of the House in November as critical, as it could be their last hold on power in Washington if Trump returns to the White House and Republicans capture the Senate.
Biden faces a new reality since last week's debate - even if he doesn't falter verbally or physically, serious concerns about his viability as a candidate are likely to linger. If he mangles words or looks unfocused or confused, he will face renewed pressure to depart.
If reelected, Biden would be 86 at the end of a second term. He is being asked by some former supporters to step aside to preserve his legacy and lessen the chances of a second Trump presidency. With just four months to go before the election, a decision needs to be made soon, they say.
Democrats, including top allies, have left the door open to having Harris at the top of the Democratic ticket.
The White House has repeatedly said the president was suffering from a cold and jet lag on the night of the debate. On Wednesday, White House Press Secretary Karine Jean-Pierre said Biden had not had any kind of medical exam since his annual physical in February.
"He did not get checked out by the doctor. It's a cold, guys. It's a cold," she said at a news briefing.
However, spokesperson Andrew Bates said on Thursday that Biden saw a doctor after the debate. "Several days later, the president was seen to check on his cold and was recovering well," he said.
Trump, 78, who made multiple false statements from the debate stage in Atlanta, falsely claimed in a video that was circulated on social media that he had driven Biden out of the race. He made disparaging comments about Harris in the same video, which the Trump campaign stood by.
On Sunday, Biden and his wife Jill are due to speak to thousands at the National Education Association in Pennsylvania. Next week he hosts dozens of world leaders at the NATO summit in Washington, and holds a rare solo news conference.
