President Joe Biden offered a new excuse for his humiliating debate performance, but he was quickly fact-checked on social media and accused of lying.

Many on the left have turned on Biden's campaign and called for his ouster after he bumbled through a debate and confirmed suspicions that his mental and cognitive abilities had diminished.

'I wasn't very smart.'

On Tuesday, the president offered a new excuse for his poor performance even as more voices joined the chorus demanding for his replacement.

“I wasn’t very smart,” said Biden to reporters about the debate.

“I decided to travel around the world a couple times, going through I don’t know how many time zones — for real I think it 15 time zones," he added.

"I didn’t listen to my staff," Biden said. "And then I almost feel asleep on stage."

He went on to apologize for his performance but added that it was "critical" for the campaign.

"It's not an excuse but an explanation," he added.

He apparently spoke for six minutes to reporters before being escorted away.

'So, this is a brazen lie.'

The excuse was immediately assailed by Biden's critics, who pointed out that it was contradicted by previously known facts. Namely, that Biden had taken more than a week to prepare for the debate.

"Biden returned from his overseas trip June 15. The debate was June 27," replied Jim Geraghty of National Review.

"The travel he references concluded almost two full weeks before the debate. Did anyone point this out?" asked Leon Wolf, managing editor of TheBlaze.

"So, this is a brazen lie. He returned twelve days before the debate, and spent the week before preparing," responded Charles C.W. Cooke of National Review. "When preparing he started at 11am each day, and then had a nap in the afternoon."

"This doesn’t fly with the reporting that Biden spent his week of debate prep starting at *11am* and also took afternoon naps. If he can’t recover from a trip to Europe in a week in those easy conditions, he just…can’t be president," replied Townhall.com managing editor Spencer Brown.

One poll found that Trump had a 6% advantage over Biden among registered voters after the debate, and far more viewers said Trump won the debate compared to those who said Biden won.

Like Blaze News? Bypass the censors, sign up for our newsletters, and get stories like this direct to your inbox. Sign up here!