President Joe Biden has responded to criticism over his age, telling supporters in a passionate speech that he will win re-election in November despite a poor debate performance that fueled concern about his candidacy.

“I know I’m not a young man, to state the obvious,” he said at a rally in the battleground state of North Carolina on Friday, a day after struggling in the televised showdown with his Republican rival, Donald Trump. “I don’t walk as easily as I used to… I don’t debate as well as I used to,” he admitted. “But I know what I do know, I know how to tell the truth, [and] I know how to do this job.”

Mr. Biden, 81, expressed his belief with his “heart and soul” that he could serve another term, as the cheering crowd in Raleigh chanted “four more years.”

Meanwhile, Trump held a rally in Virginia just hours later, where he celebrated a “big victory” in the debate, which CNN reported was viewed by 48 million people on television and millions more online. “Joe Biden’s problem is not his age,” the 78-year-old Trump said. “It’s his competence. He’s grossly incompetent.”

The former president dismissed speculation that Mr. Biden would drop out of the race, noting that he “does better in polls” than other Democrats, including California Governor Gavin Newsom and Vice-President Kamala Harris.