Still, for all the reports of a fuming president alarmed at possible impeachment, Mr. Trump rarely expresses such specific anxiety out loud, associates said. Instead he expresses frustration, anger, mania — all of which aides read like tea leaves to discern what lies beneath.

“It will be a challenge not to be consumed by it,” Mr. Short said. “It would only be human when it’s the coverage leading the news every day to be distracted, but it will be important to have the internal discipline not to be.”

No one outside of Mr. Mueller’s office, of course, knows for sure what he will report, but so far he and other prosecutors have drawn a devastating picture of a president surrounded by people who have lied to the authorities, cheated on their taxes, skirted campaign finance laws and secretly worked for foreign interests. The question is what Mr. Mueller will say about Mr. Trump.

“Does he create a story that the man never put the presidency first?” asked Doris Kearns Goodwin, whose newest book, “Leadership: In Turbulent Times,” chronicles four presidents. “There has to be a narrative. The individual things may not hit the people who support him, but if there’s an overall narrative, people may understand.”

Mr. Trump has not helped himself with decisions that opponents use to draw a narrative of a president unusually deferential to Russia, including his withdrawal of troops in Syria, which drew the public approval of President Vladimir V. Putin.

“Mueller will decide whether there’s collusion with the Russians on the election,” said Mayor Rahm Emanuel of Chicago, a former White House chief of staff to Mr. Obama. “But we can now say there’s collusion with the Russians on foreign policy, and it’s not to America’s benefit.”

More recently, Mr. Trump has taken to spending time reminiscing about the happier days of his candidacy and his 2016 victory. He spent the fall showing different groups of visitors what he calls his love letters from North Korea’s iron-fisted dictator, Kim Jong-un, expressing admiration for Mr. Trump. And he still takes joy in aspects of the job, primarily those that demonstrate power. “The roads closed for me!” he declared to friends this year after a motorcade ride.