Joe Biden appeared to zone out and looked "completely lost" as his wife Jill spoke in front of him at rally in North Carolina, a conservative commentator has claimed.

Colin Rugg, Co-Owner of conservative news outlet Trending Politics, shared a clip on X, formerly Twitter, of the President standing with his mouth open and appearing slightly confused while Jill Biden touted his achievements in office at the microphone.

"Joe stands awkwardly and looks completely lost behind his wife at a campaign rally in Raleigh, North Carolina after his disastrous debate performance," Rugg wrote, adding: "Who is the real president here?"

The clip appears to be from a broadcast of the event in Raleigh, where Biden gave a noticeably punchier performance than his showing in the CNN debate on Thursday night.

The 81-year-old's halting speech became the main talking point just hours earlier in the Atlanta debate, with his Republican challenger Donald Trump at one stage suggesting that he couldn't understand what the Democrat was saying.

In one particularly painful moment, Biden attempted to talk up his economic record before appearing to lose his train of thought.

"We would be able to wipe out his debt, clear up all those things we need to do in childcare, elder care, making sure we continue to strengthen our healthcare system, making sure we're able to make every single solitary person eligible for what I'm been able to do with dealing with everything," before misspeaking and adding: "If we finally beat Medicare..."

His performance reignited questions about his fitness for another four years in the White House, and Biden appeared to acknowledge the criticism in North Carolina, saying: "I don’t debate as well as I used to."

But he added: "I know how to do this job. I know how to get things done." Speaking for 18 minutes, Biden appeared far more animated, and he excoriated Trump for his “lies” and campaign aimed at “revenge and retribution.”

“The choice in this election is simple,” Biden said. “Donald Trump will destroy our democracy. I will defend it.”

He added, alluding to his candidacy: “When you get knocked down, you get back up.”

Michigan Gov. Gretchen Whitmer, a Democrat frequently mentioned as a 2028 contender and speculated about as a potential replacement for Biden on the ticket should he step aside, released a statement backing him on Friday.

“The difference between Joe Biden’s vision for making sure everyone in America has a fair shot and Donald Trump’s dangerous, self-serving plans will only get sharper as we head toward November,” she said.

California Gov. Gavin Newsom also dismissed questions on whether he would consider stepping in for Biden, telling reporters after the debate, “I will never turn my back on him.”

Biden’s campaign billed the Raleigh event as the largest-yet rally of his reelection bid in the state Trump carried by the narrowest margin in 2020.

He’ll then travel to New York for a weekend of big-dollar fundraisers that his campaign now needs more than ever, as it looks to stave off Trump.

Trump, who recently turned 78, has also faced questions about his mental acuity after a series of bizarre rants on the campaign trail, but appeared fluent and energised in last night's head-to-head.

But the former President also repeated falsehoods, including on abortion, taxes and the deficit, and initially avoided answering if he would accept the result of the 2024 election if it doesn't go in his favour.