“How convenient that this leaked info happened to be released at the same time preorders were made available for the book on Amazon,” read the Republican committee email. “What a joke.”

Rudolph W. Giuliani, the president’s personal lawyer, in a text message to The Washington Post said he regretted pushing Bolton for the position of national security adviser and said the president was always skeptical of Bolton. He said that Bolton “never once raised any objection to what I was doing in defending” the president, and accused him of acting cowardly.

“I never thought of him as not having the courage to deal with people man to man,” Giuliani said. “So I put him in the category of John the Backstabber.”

Aides and allies said they took solace in their belief that Trump will be acquitted regardless of whether Bolton or other witnesses appear. One senior Republican official likened the allegations in Bolton’s manuscript to the nausea that can accompany a rough boat ride — unpleasant but not fatal.

“It’s like choppy waters, but the boat is not going to sink,” the official said, speaking on the condition of anonymity to share an assessment of the Bolton announcement. “They might throw up because of seasickness, but they’re not going to die.”