When Jeanine Pirro of Fox News asked him about the health care legislation in an interview on Friday, Mr. Trump drifted back to the election, talking not only about how he had won but also about how Republicans had kept control of both houses of Congress. “We were supposed to lose all three,” he said (though few analysts expected the party to actually lose the House). But instead, “I worked very hard, and we ended up winning all three.”

The day before, in an interview with Lester Holt of NBC News, Mr. Trump returned to another favorite assertion to explain why Democrats were mad about his victory and therefore promoting what he called a false story about Russian meddling and possible collusion with his team. “The Electoral College is almost impossible for a Republican to win,” he said. “It’s very hard because you start off at such a disadvantage. So everybody was thinking they should’ve won the election. This was an excuse for having lost an election.”

Political specialists would actually say the opposite — that Republicans have a disproportionate advantage in the Electoral College, given the extra weight it gives to less-populated states and the ability of Republicans to win it twice in the past 16 years without also winning the popular vote. Either way, Mr. Trump’s point is that he won, Democrats should get over it and the F.B.I. and congressional committees should drop their investigations.

A week before firing Mr. Comey, the president challenged Mrs. Clinton’s contention that she had lost in part because of Mr. Comey’s announcement shortly before the election that he was reopening the bureau’s investigation into her emails.

“Perhaps Trump just ran a great campaign?” he wrote on Twitter.

Former aides to Mrs. Clinton said that Mr. Trump obviously could not let go. “It is remarkable,” said Ms. Palmieri, her former adviser. “Has there been a president ever who’s been that obsessed about proving that he’s legitimate?”

Mr. Ruddy argued that, from Mr. Trump’s point of view, it was the other side that could not move on. “He is totally secure with the idea that he won this election fair and square,” Mr. Ruddy said.

Other presidents have basked in their electoral victories and have seized on various data points to argue that theirs was greater than others. But few seem to have relived their elections and relitigate them as persistently as Mr. Trump has.