WASHINGTON: While Americans were celebrating the July 4 holiday with fireworks and feasts, President Joe Biden on Thursday continued to face explosive fallout from his debate against Donald Trump that has left many Democrats hungry for a replacement.

The 81-year-old has struggled since last week's debate to tamp down panic among his party, but he won the backing Wednesday of Democratic governors who gathered for an emergency meeting with him at the White House.

However, a new and potentially damaging wrinkle emerged on Independence Day, with The New York Times reporting Biden told the governors he needs more sleep and plans to curtail public events after 8:00 pm.

The revelation was according to two participants in the meeting, the Times said, and could further fuel rumblings within the party about finding a replacement candidate for November's election.

With polls showing Republican Trump extending a narrow lead after last week's debate, Biden finds himself under pressure as never before to demonstrate his capacity to lead.

"I had a bad night," Biden acknowledged to Wisconsin's Civic Media in a pre-recorded radio interview that aired Thursday.

"I screwed up. I made a mistake," he added. "That's 90 minutes on stage. Look at what I've done in 3.5 years."

The White House has insisted Biden is "absolutely not" stepping down.

Biden himself sought to appear determined he was staying in the race, telling his radio interviewer: "When you get knocked down, you just get back up."

Later at an Independence Day barbecue at the White House, he told the crowd of military personnel and their families that he was "not going anywhere."

Responding to a supporter who told him to "keep up the fight," Biden said: "You got me man. I'm not going anywhere."

A little later, Biden addressed the crowd again before the traditional fireworks display.

"We got to do what our founders did - show the world we're a nation of dignity, honour, and just devotion to one another," he said, in rare remarks without a teleprompter.

However more calls continued to come in on Thursday for Biden to step aside, heaping pressure on his upcoming engagements which include a prime time interview with ABC News on Friday and a press conference during the Nato summit next week in Washington.

British magazine The Economist became the latest major publication urging Biden to withdraw, joining The New York Times and Boston Globe editorial boards.

Meanwhile, Congressman Seth Moulton of Massachusetts became the third sitting Democratic lawmaker to call for the president to be replaced on the ticket.

"Biden has done enormous service to our country, but now is the time for him to follow in one of our founding father, George Washington's footsteps, and step aside to let new leaders rise up and run against Donald Trump," Moulton told radio station WBUR.

As the president struggles to overcome his disastrous debate performance, Kamala Harris, the nation's first female vice president, has suddenly been forced into the spotlight.

The 59-year-old former California prosecutor - who introduced Biden on stage Thursday evening - has been performing a delicate act since the debate.

She has offered unwavering support for Biden in public but is standing by as a leading contender to replace him if he steps aside.

Trump, who has remained largely - and uncharacteristically - quiet as Biden's crisis deepens, broke his silence Thursday in fierce fashion, unleashing attacks on Biden and Harris in a leaked video that he then posted on his own Truth Social account.

"I kicked that old broken down pile of crap" during the debate, Trump, sitting in a golf cart, says in the video.

"He's quitting the race. Yep, I got him out of the race. And that means we have Kamala," Trump says. "She's so bad, she's so pathetic."

He later challenged Biden to another debate, saying it would prove "prove his 'competence,' or lack thereof."

"Let's do another Debate, but this time, no holds barred - An all on discussion, with just the two of us on stage, talking about the future of our Country," Trump posted on his Truth Social platform.

He said it would be an even a higher ratings bonanza than the first debate and that he was ready "ANYTIME, ANYWHERE, ANYPLACE!!!"

 -AFP