In an interview, Mr. Christie said he had told Mr. Trump in private everything he said from the stage on Saturday. “He gets to decide what role he wants to play,” he said, adding that he hopes the former president would opt to play a more constructive one than he has recently. Mr. Trump has, for instance, warned that Republican voters wouldn’t show up at the polls unless the party’s elected officials embrace his lies about voter fraud.

“But anybody who’s talking about the past in this election is a loser,” Mr. Christie said. “They’re just going to lose because the public doesn’t want to see that.”

In addition to Mr. Christie, the other Republican who urged his party in unambiguous terms to get past Mr. Trump’s false and repeated insistences of being cheated of victory was Gov. Chris Sununu of New Hampshire.

Speaking to the optimism in the room, Mr. Sununu offered hope but also a reality check. “This week was a terrific week,” he said, “but if you think this week is going to carry us for a year, you’ve got another thing coming.”