And the vice president was eventually successful when she brought up one of Trump’s most sensitive topics: the crowd sizes at his rallies.

“I’m going to actually do something really unusual,” Harris said, “and I’m going to invite you to attend one of Donald Trump’s rallies. Because it’s a really interesting thing to watch.”

Harris criticized Trump’s behavior on the rally stage, which routinely features the former president referring to fictional characters such as Hannibal Lecter or odd claims that “windmills cause cancer.” The vice president then went further, claiming attendees “start leaving his rallies early out of exhaustion and boredom” — a claim that Trump couldn’t let pass by.

“Let me respond to the rallies. She said people started leaving. People don’t go to her rallies. There’s no reason to go,” Trump said. “And the people that do go, she’s busing them in and paying them to be there.”

“People don’t leave my rallies,” he added. “We have the biggest rallies, the most incredible rallies in the history of politics. That’s because people want to take their country back.”

The jab from Harris comes after the vice president’s campaign released an ad ahead of the debate hitting Trump on his obsession with his rally sizes, featuring a video from former President Barack Obama’s speech at the Democratic National Convention.

During that speech, Obama made a gesture while joking about crowd sizes before glancing down at his hands in a suggestive manner.

The ad then compiles footage of smaller crowds at Trump rallies before showing large and enthusiastic crowds supporting Harris.

“Tonight’s debate will present the stark choice Americans will face at the ballot box: between Vice President Harris who is fighting for the people to make our lives better, and the guy who can’t seem to stop obsessing about himself and the size of his crowds,” Harris campaign Communications Director Michael Tyler said in a statement.