'Babbling': Trump biographer predicts ex-president will be 'fumbling badly' at debate

At the upcoming presidential debate, Donald Trump will shine a spotlight on the fact that he's not more mentally sharp than President Joe Biden, according to the former president's biographer.

Tim O'Brien, who spent massive amounts of time with Trump before writing TrumpNation: The Art of Being the Donald, appeared on MSNBC on Saturday where he was asked about Trump's debate with Biden. Earlier this month, O'Brien undermined the ex-president's claim that he wasn't concerned about jail after being convicted on 34 counts.

This weekend, O'Brien was asked about Trump reportedly preparing for the debate by having several people including "Marco Rubio floating around him."

ALSO READ: EXCLUSIVE: House Republicans subpoena ex-Capitol Police intel head for Jan. 6 inquiry

"There is a danger in that, not simply because people should always prepare for debates," the biographer wrote. "Remember Barack Obama in 2012 didn't really prepare for his first debate for Mitt Romney and didn't engage fully and it really showed. It is usually more perilous for incumbent presidents than challengers."

But this debate is different, O'Brien said.

"Having said that, the format for the debate Thursday night does not play to Trump's hooliganism, which is what he has tried to do in previous debates, where he has made a show of himself. There is an audience and he can grab the mic and say something... In this debate, the mic will be off when one of the other candidates is speaking," he added. "There is no live audience and they can't have notes. I anticipate him fumbling badly on policy issues."

He went on to say that one of the important factors in this debate is "vitality, not policy."

"I think voters do have concerns about Biden's age. Trump's been getting away with this idea he is somehow more vital, more mentally acute than Joe Biden, which I don't think he is," he said, adding that Trump is just three years younger than Biden. "That's it. Three years younger and he's been babbling... on the campaign trail lately."

Watch below or click the link here.