Trump has expressed particular anger over Mulvaney’s performance in an Oct. 17 news conference in which Mulvaney stunned White House aides by saying military aid to Ukraine was withheld to pressure its government to launch investigations that could politically benefit Trump, two of the people said. Later, Mulvaney issued a statement saying the media had misconstrued his televised comments and that “there was absolutely no quid pro quo.”

Senior advisers have cautioned Trump that removing Mulvaney at such a sensitive time could be perilous, the people said — both because Mulvaney played an integral role in the decision to freeze the aid, and because of the disruption that would be caused by replacing one of Trump’s most senior aides.

“I don’t think you’ll see him going anywhere until after December,” said one Trump adviser, who like others spoke on the condition of anonymity to discuss private conversations. “But the president was very unhappy with that press conference. That was a very bad day for the president.”