Jill Biden says she thought Joe Biden was having a stroke during 2024 debate

The former first lady has a book coming out June 2.

Former first lady Jill Biden said she was "frightened" when watching her husband, former President Joe Biden, in his first and only debate performance during the 2024 presidential election and thought he was having a stroke on stage.

"I wasn't horrified, I was frightened, because I had never ever seen Joe like that before or since, never," Biden said to CBS News Sunday Morning's Rita Braver in an interview airing Sunday on CBS.

The broadcaster has released an excerpt of the interview.

"I don't know what happened. I mean, when I, as I watched it, I thought, 'Oh my God, he's having a stroke,' and it scared me to death," the former first lady said later on in the clip.

After Biden's halting performance during the June 2024 debate, many in the Democratic Party called on him to drop out of the presidential election -- which he did about three weeks later, endorsing Vice President Kamala Harris.

Immediately following his lackluster performance, Biden and his wife sought to reassure supporters that he was up to the task of serving as president for four more years.

At a rally the day after the debate, Biden acknowledged his shaky performance.

"Folks, 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, but ... I know how to tell the truth. I know right from wrong, and I know how to do this job," he told the crowd.

At a fundraiser in New York City’s Greenwich Village following the debate, the former first lady also addressed his debate performance.

"So, let's talk about last night's debate, because I know it's on your minds," she reportedly said. "As Joe said earlier today, he's not a young man. And you know, after last night's debate, he said, 'You know, Jill, I don't know what happened. I didn't feel that great.' And I said, 'Look, Joe, we are not going to let 90 minutes define the four years that you've been president.'"

In an interview with ABC News' George Stephanopoulos a week after the debate, Biden said his poor performance was not the result of any serious condition and chalked it up to a "bad episode," saying recent international travel and a bad cold had left him exhausted.

"No indication of any serious condition. I was exhausted. I didn't listen to my instincts in terms of preparing and -- and a bad night," he said.

The interview with CBS News comes ahead of the former first lady's book, "View from the East Wing: A Memoir," which is being released on June 2.