Vice President Mike Pence said the ongoing impeachment hearings sunk to a “new low” after Stanford law professor Pamela Karlan took a potshot at President Donald Trump’s youngest son, 13-year-old Barron Trump, while testifying before the House Judiciary Committee on Wednesday.

“The impeachment hearings today reached a new low,” Pence told reporters in Holland, Michigan, shortly after the incident. “I just heard at the hearing today, one of the Democrats’ witnesses actually used the President and first lady’s 13-year-old son to justify their partisan impeachment. Democrats should be ashamed.”

“Enough is enough,” he added. “This sham impeachment should end, and congress should get back to work on issues that are important to the American people.”

Karlan, a Democrat witnesses with a history of disparaging remarks about President Trump and his administration, sparked blowback when she referenced Barron while explaining the president’s constitutional limitations.

“Contrary to what President Trump has said, Article 2 does not give him the power to do anything he wants, and I’ll just give you one example that shows you the difference between him and a king, which is the Constitution says there can be no titles of nobility, so while the president can name his son Barron, he can’t make him a baron,” the law professor explained.

Melania Trump fired off a pointed Twitter about Karlan’s quip, writing that “a minor child deserves privacy and should be kept out of politics.”

A minor child deserves privacy and should be kept out of politics. Pamela Karlan, you should be ashamed of your very angry and obviously biased public pandering, and using a child to do it. — Melania Trump (@FLOTUS) December 4, 2019

“Pamela Karlan, you should be ashamed of your very angry and obviously biased public pandering, and using a child to do it,” she added.

White House press secretary Stephanie Grisham called the moment “classless.”

“Classless move by a Democratic ‘witness.’ Prof Karlan uses a teenage boy who has nothing to do with this joke of a hearing (and deserves privacy) as a punchline. And what’s worse, it’s met by laughter in the hearing room. What is being done to this country is no laughing matter,” she wrote.

Classless move by a Democratic “witness”. Prof Karlan uses a teenage boy who has nothing to do with this joke of a hearing (and deserves privacy) as a punchline. And what’s worse, it’s met by laughter in the hearing room. What is being done to this country is no laughing matter. — Stephanie Grisham (@PressSec) December 4, 2019

The professor later apologized for invoking Barron Trump — but said the president should also express remorse for his own alleged misconduct.

“I want to apologize for what I said earlier about the president’s son. It was wrong of me to do that. I wish the president would apologize, obviously, for the things that he’s done that’s wrong, but I do regret having said that,” she said.

Karlan testified alongside University of North Carolina Law School’s Michael Gerhardt, Harvard Law School’s Noah Feldman, and George Washington University law professor Jonathan Turley, the sole Republican witness, as part of the House Judiciary panel’s hearings on impeachment.