Biden's aides said his debate performance was poor because he struggles to function after 4 p.m., report says

• Joe Biden's aides defended his debate performance, citing his limited optimal hours, Axios said.
• Biden performs best between 10 a.m. and 4 p.m., his aides told the publication.
• Some blamed his performance on overpreparation by aides, The Washington Post reported.

President Joe Biden's aides have defended his debate performance, saying he struggles to function outside a six-hour window during the day, Axios reported.

The publication, citing people close to the president, said Biden worked best between 10 a.m. and 4 p.m.

According to the anonymous aides who spoke with Axios, Biden is more likely to make verbal mistakes and become tired outside this time period or while traveling abroad.

Business Insider could not independently verify the comments.

Biden's aides have also come under scrutiny. The Washington Post reported that some in Biden's inner circle blamed his poor performance on overpreparation.

Others said that too many aides were involved in his weeklong preparations at Camp David, the report added.

Biden and former President Donald Trump went head-to-head in their first debate of the year on Thursday at 9 p.m. ET in Atlanta.

Commentators and politicians deemed the debate disastrous for Biden and questioned whether he was too old for another term as president.

During parts of the debate, Biden, who's 81, made confusing statements and appeared to forget what he was saying midsentence. For example, when asked about the national debt, Biden stumbled and said, "We finally beat Medicare."

"I spent half my career being criticized for being the youngest person in politics. I was the second-youngest person ever elected in the United States Senate — and now I'm the oldest," Biden said during the debate when asked to address concerns about his age.

His aides' comments seem to contradict Biden's own argument that age shouldn't be a factor in the presidential race.

"My fellow Americans, the issue facing our nation isn't how old we are: It's about how old our ideas are," he said during the State of the Union address in March.

"You can't lead with ancient ideas that only take us back," he added.

He made a similar point in May during an interview with the MSNBC host Stephanie Ruhle.

"I have acquired a hell of a lot of wisdom and know more than the vast majority of people," he said. "And I'm more experienced than anybody that's ever run for the office. And I think I've proven myself to be honorable as well as also effective."

Biden has acknowledged he performed poorly in the debate but downplayed its importance.

"I don't walk as easy 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 Friday to the crowd at a Raleigh, North Carolina, campaign rally.

"I know how to tell the truth. I know right from wrong. And I know how to do this job. I know how to get things done," he added.

Representatives for the Biden campaign did not immediately respond to a request for comment.