Palm Beach, Florida - Donald Trump said he thinks President Joe Biden will stay in the race for the White House despite calls for him to drop out over concerns about his mental fitness.

"I think he, you know, might very well stay in," Trump told Sean Hannity on Fox News Monday, in his first interview since Biden's dismal performance in their presidential debate late last month.

"He's got an ego and he doesn't want to quit," Trump said.

The Republican also gave his first detailed account of the CNN-hosted debate in Atlanta, during which Biden often lost his train of thought and at times spoke incoherently, looking dazed.

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"I will tell you. It was a strange debate, because within a couple of minutes, the answers given by him were, they didn't, they didn't make a lot of sense," Trump said.

Trump, who has so far avoided making hay of Biden's woes, said he intentionally did not look much at his rival as he spoke.

"I did take a couple of peeks when he was in the midst of giving some really bad answers," Trump said. "They weren't even answers. They were just words put together that had no meaning or sense."

Trump also went on his own typically rambling tangents during the interview, railing about mass deportations of migrants and agreeing with Hannity in the conviction that "we're going to have a terror attack."

Bizarrely, he also claimed "Jimmy Carter is the happiest guy around" because the 99-year-old's administration supposedly compares favorably to Biden's.

Carter has been in hospice care for over a year and lost his wife in November.