President Donald Trump on Sunday referred to Rep. Adam Schiff, the incoming chairman of the House Intelligence Committee “Adam Schitt” after Schiff criticized the appointment of Matthew Whitaker as acting attorney general.

So funny to see little Adam Schitt (D-CA) talking about the fact that Acting Attorney General Matt Whitaker was not approved by the Senate, but not mentioning the fact that Bob Mueller (who is highly conflicted) was not approved by the Senate! — Donald J. Trump (@realDonaldTrump) November 18, 2018

“Good one,” Schiff responded.

Wow, Mr. President, that’s a good one. Was that like your answers to Mr. Mueller’s questions, or did you write this one yourself? https://t.co/Yd27sayt7C — Adam Schiff (@RepAdamSchiff) November 18, 2018

Speaking to Martha Raddatz on ABC’s “This Week” earlier Sunday, Schiff said he thought Whitaker’s appointment was “unconstitutional”: “He’s clearly a principal officer, and the fact that he is a temporary principal officer doesn’t mean that that is any less subject to Senate confirmation. Constitutionally, it has to be subject to confirmation.”

“There’s a succession statute for the Justice Department, which makes it different from other departments,” Schiff asserted.

The state of Maryland has argued that Whitaker’s appointment is unconstitutional. The Justice Department’s Office of Legal Counsel put out a memo defending the appointment.