Ben Carson, one of the earliest former rivals to endorse Donald J. Trump, has a new role, according to a confidant: emissary from Mr. Trump to the remaining holdouts from the Republican primary field.
The confidant, Armstrong Williams, said on Thursday that Mr. Carson had been placing calls and “reaching out to everyone,” and planned to make the case that despite Mr. Trump’s insults in the primary race, the party needs to come together.
The outreach would include Senator Ted Cruz, Senator Marco Rubio and Jeb Bush, all of whom were frequent targets of insults from Mr. Trump during the primary campaigns.
“He can say, ‘He’s done nothing to you that he has not done worse to me,’ ” Mr. Williams said, referring to Mr. Trump’s mockery of Mr. Carson, a retired neurosurgeon, before the Iowa caucuses this year.
Hope Hicks, Mr. Trump’s spokeswoman, did not respond to an email about Mr. Carson’s role.
Mr. Carson, who endorsed Mr. Trump in March a week after ending his White House bid, has had multiple roles in the Trump campaign, including identifying potential vice-presidential candidates and as a go-between with Representative Paul D. Ryan, the House speaker, who met with Mr. Trump on Thursday in search of party unity.
Mr. Carson stepped away from the committee vetting vice-presidential possibilities after it was reported on Tuesday that Corey Lewandowski, Mr. Trump’s campaign manager, would head up that operation, Mr. Williams said. He added that it was Mr. Carson’s decision — not that of Mr. Trump or Mr. Lewandowski, who has been reported to be jostling with other senior advisers for primacy in the campaign.
“Trump wanted to give Dr. Carson the title of heading it up, but he didn’t want it,” Mr. Williams said, referring to the vice-presidential committee. “He enjoys the freedom of having his life back and being an adviser.”
“When the announcement came out of who was heading it up, it was a surprise,” he added, referring to Mr. Lewandowski’s role.
The campaign has yet to formally comment on whether Mr. Lewandowski is heading the vice-presidential search, which was first reported by The Washington Post.
Mr. Trump told The Associated Press after that report that a team of people on the campaign would be involved. “Honestly, we’re all running it. It’s very much a group effort,” Mr. Trump told The A.P., adding in that interview that Mr. Carson would be involved.
Mr. Williams, who is Mr. Carson’s business manager, said that Mr. Carson gave Mr. Trump several names for vice president — but not his own. “He is not interested at all” in being vice president, Mr. Williams insisted.
On Tuesday, Mr. Carson spoke by phone with Mr. Ryan to try to overcome the speaker’s hesitancy to endorse Mr. Trump. “What Dr. Carson took his time to do was tell Speaker Ryan what a good listener Mr. Trump was,” according to Mr. Williams.
Mr. Carson maintained a mild manner throughout his presidential run even in the face of Mr. Trump’s ridicule of his biography, parts of which Mr. Trump implied were concocted.
“The world laughed at him when he endorsed Mr. Trump,” Mr. Williams said. “And still, he was determined to unify the party.”
In reaching out to other defeated candidates, Mr. Williams said that Mr. Carson planned to argue that they should come on board to prevent a Democratic president from naming future Supreme Court justices.
“The toughest one is going to be Bush,” he said. “But listen, that can change.”