The people briefed on the move said that it reflects Mr. Trump's realisation that his campaign was at a crisis point. But it indicates that the candidate, who has chafed at making the types of changes his current aides have asked for even though he had acknowledged they would need to occur, has decided to embrace his aggressive style for the duration of the race.

Both Mr Bannon and Ms Conway are close with Robert and Rebekah Mercer, the father-and-daughter conservative donors who have become allies of Mr Trump and are funding a "super PAC" that is working against Hillary Clinton.

Ms Conway has past presidential experience in primary races, but the role in a general election represents a new one for her. She is well liked by Mr Trump's daughter, Ivanka, and his son-in-law, Jared Kushner, who had been serving as the de facto campaign manager.

Mr Bannon has no experience with political campaigns, but he represents the type of bare-knuckled fighter that the candidate had in Corey Lewandowski, his combative former campaign manager, who was fired on June 20.

Breitbart News Stephen Bannon is Donald Trump's new campaign CEO. AP

Mr Bannon has been a supporter of Mr Trump's pugilistic instincts, which the candidate has made clear in interviews he is uncertain about whether he wants to suppress. He is also deeply mistrustful of the political establishment, and his website has often been critical of House Speaker Paul D. Ryan and Senator Mitch McConnell, the majority leader.

Rudolph W. Giuliani, the former mayor of New York City 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 US history.

It was not clear what the promotions would mean for Mr Manafort, who had initially been hired to steer Mr Trump through what appeared to be a protracted fight for delegates.


Mr Manafort rose in power after repeated clashes with Mr Lewandowski, who 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.

Kellyanne Conway, president and chief executive officer of Polling Co, and a senior adviser to Donald Trump, is Trump's new campaign manager. Bloomberg

Mr Lewandowski, now a paid CNN commentator, has denied that it was the case, 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 his Florida properties. He 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.

The candidate has bucked repeated efforts to rein in his impulsive behaviour, committing repeated gaffes after telling he aides he planned to adopt a more presidential tone.

His behaviour 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 on Sunday in meetings at Mr Trump's golf club at Bedminster, N.J. Roger Ailes, the former head of Fox News, also met with Mr Trump that day, and he will be part of efforts to prepare Mr. Trump in his debate against Mrs Clinton and with 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 $US12.7 million ($A16.6 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.

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 New York Times.

Time, Mr. Pence added, was on their side. "It's preseason, for heaven's sake," he said. "The gun starts on Labor Day."

The New York Times