“This (Friday) morning Paul Manafort offered, and I accepted, his resignation from the campaign. I am very appreciative for his great work in helping to get us where we are today, and in particular his work guiding us through the delegate and convention process,” Trump said.
“Paul is a true professional and I wish him the greatest success,” the 70-year-old business tycoon said.
Manafort’s role was reduced after Trump elevated two aides to senior positions on Tuesday, appointing Breitbart News chief Steve Bannon as campaign chief executive officer and Kellyanne Conway as campaign manager.
Manafort, who had once lobbied for pro-Inter-Services Intelligence and anti-India groups, had been recently attracting negative publicity for his alleged lobbying activities in Ukraine.
Manafort had joined the campaign after Trump’s historic wins in the Republican primaries.
He successfully led the campaign in the Republican National Convention in Cleveland, Ohio, where Trump was formally nominated as the party’s presidential nominee.
Trump’s popularity rating had been falling down after the convention.
Manafort told Trump he was becoming a distraction and he wanted to end that, a Trump source was quoted as saying by CNN.
The resignation comes as the campaign seeks to correct course after weeks of damaging controversies and self-inflicted wounds, effectively evaporating Trump’s steady footing against Democratic candidate Hillary Clinton in the polls and his post-convention bump. Trump is now trailing Clinton in every major poll.
The most damaging for Trump was his attack on a Gold Star family -- who lost their son, Army Captain Humayun Khan, while he served in Iraq -- for speaking out against him at the Democratic National Convention. He later refused to apologise or express regret.
Manafort’s personal business dealings have also come under intense scrutiny in recent weeks, amid damaging questions over his ties to foreign governments and indications that he might have received $12 million (Rs 80 crore) in undisclosed cash payments, according to the Washington Post.
The alleged payments, which Manafort denied, were noted in a ledger kept by former Ukraine president Viktor Yanukovych’s political party. Since then, more evidence has surfaced that raised concerns about his ties to the Kremlin.
One Grand Old Party strategist was quoted as saying that Manafort was undone by the combination of revelations about his work in behalf of pro-Russian forces in Ukraine and the elevation of Conway and Bannon.