President Donald Trump likes to dismiss polls and judge popularity by crowd size ― to the point of inflating his own numbers. And that, said MSNBC’s Nicolle Wallace, may be why the Democratic candidate he fears most isn’t former Vice President Joe Biden.

It’s Sen. Kamala Harris (D-Calif.), who kicked off her campaign earlier this year in front of a massive crowd of 20,000 people in Oakland.

“Her crowds spooked him,” Wallace said.

“In Trump’s mind, that’s the measure, that’s the poll,” Axios reporter Jonathan Swan said on “Deadline: White House.” “Crowds don’t lie.”

The show’s panel also discussed a New York Times report that said Harris was rebooting her campaign with more direct attacks on the president. Times reporter Annie Karni said that while Trump had labeled Biden as “Sleepy Joe” and Sen. Bernie Sanders (I-Vt.) as “Crazy Bernie,” he hadn’t said a whole lot about Harris.

“She is notably one candidate in the wide field that he doesn’t seem to know how to take on,” Karni said.

Reminded that Trump had once called her a “nasty wit,” Karni said the insult was “almost like a compliment.”

See the full conversation above.