LAS VEGAS — Donald J. Trump has shaken up his presidential campaign for the second time in two months, hiring a top executive from the conservative website Breitbart News and promoting a senior adviser in an effort to right his faltering campaign.
Stephen Bannon, the executive chairman of Breitbart News LLC, will become the Republican campaign’s chief executive, and Kellyanne Conway, a senior adviser and pollster for Mr. Trump and his running mate, Gov. Mike Pence of Indiana, will become the campaign manager.
Paul Manafort, the campaign chairman, will retain his title, and his deputy, Rick Gates, is expected to receive a new one.
The news, first reported by The Wall Street Journal, was confirmed early Wednesday by Ms. Conway in a brief interview, but she rejected the idea that the changes amounted to a shake-up and said that Mr. Manafort was not being diminished.
“It’s an expansion at a busy time in the final stretch of the campaign,” she said.
“We met as the ‘core four’ today,” Ms. Conway added, referring to herself, Mr. Bannon, Mr. Manafort and Mr. Gates.
People briefed on the move said that it reflected Mr. Trump’s realization that his campaign was at a crisis point. But it also indicates that the candidate — who has chafed at making the types of changes his current aides have asked for, even though he has acknowledged they need to occur — has decided to embrace his aggressive style for the duration of the race, come what may.
Both Ms. Conway and Mr. Bannon, whose news organization has been very favorable to Mr. Trump since he entered the primaries, are close with Robert and Rebekah Mercer, the father-and-daughter conservative donors who have become allies of the candidate and are funding a “super PAC” that is working against Hillary Clinton.
Ms. Conway has experience in presidential primary races, but a role in a general election represents a new one for her. She is well liked by Mr. Trump’s daughter Ivanka and her husband, Jared Kushner, who had been serving as the de facto campaign manager. And she is a veteran pollster and strategist whom Mr. Trump trusts.
A frequent cable news presence, Ms. Conway now is expected to travel with Mr. Trump, filling a void created when Corey Lewandowski, his combative former campaign manager, was fired on June 20.
Mr. Bannon has no experience with political campaigns, but he represents the type of bare-knuckled fighter that the candidate had in Mr. Lewandowski. And he shares many of Mr. Trump’s hard-edge, nationalist and populist views.
Mr. Bannon has been a supporter of Mr. Trump’s pugilistic instincts, which the candidate has made clear in interviews he is uncertain about suppressing. He is also deeply mistrustful of the political establishment, and his website has often been critical of Speaker Paul D. Ryan and Senator Mitch McConnell, the majority leader.
Rudolph W. Giuliani, the former mayor of New York who has become a close Trump adviser, has also urged the candidate to dig in and prepare to fight harder, and in a more focused way, in what has quickly become one of the nastiest presidential campaigns in modern United States history.
Mr. Manafort announced the changes in a conference call Wednesday morning and sounded upbeat, according to one person briefed on the call. He has told others that he is content with the changes and does not consider them destabilizing.
Mr. Manafort, who was hired to steer Mr. Trump through what appeared to be a protracted fight for delegates, rose in power after repeated clashes with Mr. Lewandowski.
Mr. Lewandowski was ultimately fired with the help of Mr. Trump’s adult children, who believed the campaign manager was trying to spread negative stories about Mr. Kushner.
Mr. Lewandowski, now a paid CNN commentator, has denied doing so, and he and Mr. Trump still speak frequently, with the candidate seeking his advice.
Mr. Lewandowski’s troubles began, in part, when he was accused by a female Breitbart reporter, who worked for Mr. Bannon, of grabbing her roughly after a news conference at one of Mr. Trump’s Florida properties. Mr. Lewandowski was charged with assault, but prosecutors declined to proceed with the case, which was dropped.
People briefed on the reshuffling were adamant that Mr. Trump’s children would seek to block a return by Mr. Lewandowski. And they insisted that staff departures resulting from the changes would be few.
Mr. Trump has bucked efforts to rein in his impulsive behavior, committing repeated gaffes after telling his aides he planned to adopt a more presidential tone.
His behavior has angered the party’s top figures, who have openly expressed concern about preserving Republican majorities in the House and Senate in light of Mr. Trump’s performance in the polls.
The moves were hammered out beginning on Sunday in meetings at Mr. Trump’s golf club at Bedminster, N.J. Roger Ailes, the former chairman of Fox News, also met with Mr. Trump that day, as The New York Times reported on Tuesday, and he will be part of efforts to prepare Mr. Trump in his debate against Mrs. Clinton and other tasks, according to three people briefed on the discussions.
Mr. Manafort had also come under increasing scrutiny over his ties to Ukraine for elections he worked on as an international consultant, including handwritten ledgers showing he was designated to receive $12.7 million in undisclosed cash payments from a pro-Russian political party from 2007 to 2012. Yet it remains to be seen whether a new chain of command can ultimately fix the problem: the candidate’s lack of discipline and desire to punch back at nearly any critic.
After a series of recent controversies — including Mr. Trump’s assertion that Russia should hack Mrs. Clinton’s emails; his criticism of a Muslim-American Gold Star family; and his suggestion that Second Amendment supporters could revolt against Mrs. Clinton — the candidate began trying anew to appear moderated in tone.
After a series of recent controversies — including Mr. Trump’s assertion that Russia should hack Mrs. Clinton’s emails; his criticism of a Muslim-American Gold Star family; and his suggestion that Second Amendment supporters could revolt against Mrs. Clinton — the candidate began trying anew to appear moderated in tone.
On Monday, he delivered a speech on terrorism using a teleprompter rather than the off-the-cuff style he prefers. And on Tuesday, he offered yet another scripted address, this time on law and order.
Mr. Pence, too, has privately worked to quell the growing concerns surrounding the Republican ticket. At the annual meeting of the Republican Governors Association in Colorado on Tuesday, Mr. Pence used his keynote speech to offer “encouragement” — a word he used several times — and reassurance to the crowd.
“We’re still winning hearts and minds every day despite an avalanche of negative media coverage,” Mr. Pence said during the closed-door session, according to audio provided to The Times.
Time, Mr. Pence added, was on their side. “It’s preseason, for heaven’s sake,” he said. “The gun starts on Labor Day.”
