Rep. Maxine Waters, California Democrat, repeated her call for Congress to impeach President Trump after he called her a “very low I.Q. individual” at his Saturday rally.

Mr. Trump told the crowd that “we have to defeat Nancy Pelosi and Maxine Waters, a very low I.Q. individual,” then referred to her ongoing push for him to be impeached.

“Ever see her? You ever see her? ‘We will impeach him! We will impeach the president,’” he said at the rally in Moon Township, Pennsylvania. “But he hasn’t done anything wrong. ‘It doesn’t matter, we will impeach him.’ She’s a low I.Q. individual. You can’t help it. She really is.”

Ms. Waters responded later that night by slamming the president’s brainpower at the Human Rights Campaign’s annual dinner in Los Angeles.

“Don’t forget, this man who’s disparaging me has been called stupid, ignorant, uninformed, unhinged and a moron by his own staff and appointees,” Ms. Waters told the crowd at the J.W. Marriott. “And so he had the nerve to attack me.”

Before her speech, she told the Advocate that she believes the case for impeachment is stronger than ever, citing the investigation into Russian collusion by special counsel Robert Mueller.

“I’ve always believed that there was enough there certainly to impeach him, and I believe even more so now that Mueller has been more than connecting the dots,” she said.

She added that she was “not surprised at all” by his comments, and that she thought the impeachment talk “bothers him a lot.”

“I’ve been saying some things about him for a while. I think it’s gotten to him, finally. I’ve been very vocal, and I’ve been very confrontational almost,” she said.

The congresswoman also took a jab at the intelligence of a member of the Trump cabinet, Housing and Urban Development Secretary Ben Carson.

“Under Secretary Carson’s leadership—that’s Ben Carson I’m talking about. That’s the one that they say is so brilliant? Brain surgeon? Send him back to the operating room. We don’t need him in HUD,” said Ms. Waters in a video of the speech posted by the Advocate.

Treasury Secretary Steven Mnuchin was pulled into the back-and-forth Sunday by “Meet the Press” host host Chuck Todd, who grilled him over the president’s statements at the rally, including the “low I.Q.” remark.

“You know he likes to put names on people,” said Mr. Mnuchin. “He did that through the entire presidential election, including all the Republicans that he beat. These are campaign rally issues.”

An irate Todd asked if that was “acceptable behavior for the rest of the administration, too.”

“This is something that is at a campaign rally and the president likes making funny names,” said Mr. Mnuchin.

Mr. Trump spoke at the rally to drum up support for Republican Rick Saccone, who’s running in Tuesday’s special congressional election against Democrat Conor Lamb.