A badly wounded Joe Biden looked to get his reelection campaign back on track Friday after a debate performance that unnerved supporters and left allies of Donald Trump unable to conceal their glee.

Democrats had hoped to see the president defiantly answering critics who say he is too old for a second term while hammering Trump on his criminal record and the threat they say he poses to democracy. 

Instead, many acknowledged, they got a faltering display from a candidate who sounded hoarse for much of the showdown, stumbled over words, pulled punches, often stared open-mouthed and looked confused.  

"There are no two ways about it -- that was not a good debate for Joe Biden," Democratic former White House communications chief Kate Bedingfield told host network CNN as the curtain came down on the match-up.  

David Axelrod, a senior advisor in Barack Obama's administration, said Biden's performance had "confirmed people's fears" about an 81-year-old being too old for the Oval Office. 

The president, who had spent days in mock debates at his Camp David retreat, was scheduled to begin the clean-up Friday with his largest event of the campaign, in the battleground state of North Carolina.

'Sore throat'

Facing tough questions over his performance and immediate future, he told reporters he had done "well" as he stopped off at an Atlanta Waffle House with First Lady Jill Biden after coming off stage.

He added that he was croaking because of a "sore throat" and that, in any case, it is "hard to debate a liar."

Although Biden managed to pin down Trump on abortion rights and his role in the violence that marred the 2021 handover, he waited bafflingly long -- almost 45 minutes -- to bring up Trump's felony convictions and other legal woes in any detail.

He spoke under his breath and appeared at times to lose focus, pausing for several seconds after stumbling in the opening stages.

Trump's performance was far from accomplished -- his verbal fusillades were littered with falsehoods and he dodged several times when asked what he would do about the opioid crisis ravaging middle-class families.

He also refused to clearly commit to accepting the results of November's election, playing into the narrative that he has little respect for democracy or the rule of law.

CNN reported that while Biden made nine false or misleading statements, Trump made a staggering 30, including "egregious" falsehoods on abortion, the US Capitol insurrection, health care and NATO.

But the Republican -- who is countering Biden's rally with an appearance of his own in Virginia on Friday -- largely avoided the rhetorical landmines that exploded under Biden. 

A Biden replacement?

At one point, the president bizarrely declared that "we finally beat Medicare," as the discussion turned to funding the health insurance program for seniors.

As the disappointment of Biden's showing registered with Democrats, there was even talk of finding a new candidate before the Democratic convention in August.

"There's been a lot of chatter in our circles about Newsom," one party strategist told political outlet The Hill -- although California governor Gavin Newsom quickly shut down suggestions that he could take Biden's place.

In the Trump corner, pundits reveled at how the night turned out.

Keith Nahigian, a Republican veteran of six campaigns who helped prepare multiple election candidates including John McCain for debates, told AFP that Biden's performance was "the worst I've ever seen."

"Biden called for this debate a few months ago. He pushed for this debate. I think he just sunk his presidency," he added. 

Ralph Reed, chairman of the conservative Faith and Freedom Coalition, compared the debate to a prize fight "that should have been stopped in the early rounds."