President Donald Trump mocked Joe Biden for having “choked” at the first Democrat presidential debate when confronted by Sen. Kamala Harris (D-CA) over his record on busing.

“Harris hit him with a pretty easy question on busing,” Trump said during a campaign rally in Greenville, North Carolina on Wednesday. “I would say that’s pretty easy, and he choked. He choked and then he said, oh, ‘I’m sorry, I ran out of time.'”

At the debate last month, Harris centered her criticism on Biden’s recent decision to praise the “civility” of two segregationist Democrats, the late-Sens. James Eastland (D-MS) and Herman Talmadge (D-GA), while touting his record of forging “consensus” in Congress.

“I agree with you when you commit yourself to the importance of finding common ground,” Harris said, “but I also belie, and it’s persona, and it was hurtful to hear you talk about the reputations of two United States senator who built their reputations and career on the segregation of race in this country.”

Despite having invoked the segregationist Democrats before, Biden never discussed exactly what they were able to accomplish together. Harris, though, was quick to point out at the debate that both Talmadge and Eastland were allies in his campaign against busing to integrate public schools.

“It was not only that, but you also worked with them to oppose bussing,” she said. “There was a little girl in California who was part of the second class to integrate her public schools and she was bussed to school every day. That little girl was me. So I will tell you that on this subject, it cannot be an intellectual debate… we have to take it seriously.”

Biden attempted to defend himself by claiming Harris had mischaracterized his record. Instead of providing evidence to dispute the mischaracterizations, however, the former vice president only muddled his position on busing and inaccurately claimed to never have offered praise for racists.

After the debate, Biden’s own team was reportedly “freaking out” about his poor performance. Biden’s campaign appeared correct to worry, as most political observers agreed that Biden underperformed and was caught off the guard by the brunt of Harris’s criticism. Recent FEC filings show Biden’s team took the issue seriously enough that they hired a speech coach, renowned for his work with former President Bill Clinton, one day after the debate.

On Wednesday, Trump went further by claiming that Biden’s inability to wage a proper defense showed he was “not prepared” to be president.

“He’s not prepared,” Trump said. “He’s not mentally prepared, that’s his problem.”