Returning with a bang following a forgettable round of debate with Donald Trump, US President Joe Biden on Friday vowed to keep fighting against what he framed as an existential threat to America.

In his first campaign following the debate, Biden while addressing  at the North Carolina state fairgrounds in Raleigh, Biden was quoted as saying by The Guardian: " When you get knocked down, you get back up.”

“I know what millions of Americans know," he said.

“I don’t walk as easily as I used to, I don’t speak as smoothly as I used to, I don’t debate as well as I used to,” he said referring to the criticisms he faced following the debate.

"I know what I do know. I know how to tell the truth,"  he said.

Targeting his opponent to return to the White House, Donald Trump, Biden said: "I spent 90 minutes on a stage debating a guy who has the morals of an alley cat.”

“I think he [Trump] set a new record for the number of lies told at a single debate," he said slamming the former US President.

Biden,81, faced tremendous criticisms following his unexpected show during the debate with Trump.

Biden's verbal stumbles and occasionally meandering responses raised concerns that he might not be suitable to serve the country for another term.

The USA will vote to elect a new President later this year.

Admitting that it was a 'bad debate', former president Barack Obama has voiced his support for Biden.

"Bad debate nights happen. Trust me, I know. But this election is still a choice between someone who has fought for ordinary folks his entire life and someone who only cares about himself. Between someone who tells the truth; who knows right from wrong and will give it to the American people straight — and someone who lies through his teeth for his own benefit. Last night didn’t change that, and it’s why so much is at stake in November," he posted on X.

Another former President Bill Clinton said: " I’ll leave the debate rating to the pundits, but here’s what I know: facts and history matter. Joe Biden has given us 3 years of solid leadership, steadying us after the pandemic, creating a record number of new jobs, making real progress solving the climate crisis, and launching a successful effort in reducing inflation, all while pulling us out of the quagmire Donald Trump left us in. That’s what’s really at stake in November."

Meanwhile, the New York Times editorial board asked Biden to drop out from the Presidential race.

In its editorial, the newspaper said: " The clearest path for Democrats to defeat a candidate defined by his lies is to deal truthfully with the American public: acknowledge that Mr. Biden can’t continue his race, and create a process to select someone more capable to stand in his place to defeat Mr. Trump in November."