Washington   -   US President Joe Biden took to the airwaves on July 4 fighting to show he is fit to run for re-election and serve another term, trying to douse Democratic panic triggered by his disastrous debate with Donald Trump. As Americans gather for their Independence Day holiday, concern has swelled over the 81-year-old incumbent’s mental acuity, with rumblings within his party about finding a replacement candidate before November’s election.

And with polls showing Republican Trump extending a narrow lead after last week’s televised showdown, Biden finds himself under pressure as never before to demonstrate his capacity to lead.

p“I had a bad night,” Biden acknowledged to Wisconsin’s Civic Media in a radio interview recorded the day before it 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 Biden campaign has been desperate to reassure Democratic donors, voters and lawmakers that the president’s dismal performance against Trump was a one-off. He repeated that message in an emergency meeting Wednesday with Democratic governors, who pledged their continued support, attendees said afterward. The White House has insisted Biden is “absolutely not” stepping down as the party’s presidential nominee.

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.”

As a signal of the international concern swirling over Biden’s status, British magazine The Economist became the latest major publication to call on Biden to withdraw, joining The New York Times and Boston Globe whose editorial boards this week called for the president to bow out of the race.

The uncertainty simmered ahead of the embattled president’s much-anticipated television interview Friday with ABC News, an event most of political Washington -- and perhaps the nation -- will be watching closely to see whether Biden can indeed bounce back from his faltering debate performance.

All eyes will also be on a Biden campaign rally set for Friday in Madison, Wisconsin, one of the battleground states seen as crucial for a Biden victory.

For July 4 Biden remains in Washington, where he and First Lady Jill Biden were to host a White House barbecue with military personnel and their families.

“As we celebrate the Fourth of July, I’m grateful for the countless service members who are the backbone of who we are as a nation. Their service reminds us that democracy is never guaranteed-every generation must fight to maintain it,” Biden said on X, the former Twitter.

In the evening Biden delivers remarks -- again with his every move and tone likely scrutinized -- before observing a fireworks display over Washington, accompanied by Vice President Kamala Harris.

The nation’s first female VP is suddenly in the spotlight as Democrats weigh a potential Harris candidacy.

The 59-year-old has been unwaveringly supportive of Biden in public. But she is performing a delicate high-wire act, cheerleading for her boss while standing by as a leading contender to replace him if he ends his reelection bid.

Trump, who has remained largely -- and uncharacteristically -- quiet as the Biden crisis deepens, broke his silence Thursday in fierce fashion, unleashing attacks on both 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, seen 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.”

Biden’s Wisconsin rally, and a press conference set for next week, are aimed at proving his capacity to speak impromptu, engage with voters and reporters, and generally to dismiss the doubts that have surged since his debate debacle.

Two polls released Wednesday compounded the concern, including one post-debate survey by the Times that showed Trump with his biggest lead ever over Biden -- 49 percent to 43 percent of likely voters.