Paul Manafort resigned as Donald Trump's campaign chairman Friday, days after the GOP presidential hopeful brought in Breitbart News' Steve Bannon as campaign CEO.
"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 in a statement. "Paul is a true professional and I wish him the greatest success."
Earlier this week, Trump turned to Bannon to head the floundering campaign and named veteran pollster Kellyanne Conway as campaign manager. The announcement of the changes said Manafort would stay on as chairman of the campaign.
Manafort, 67, had drawn scrutiny after recent reports linked him to former Ukrainian President Viktor Yanukovych, a Vladimir Putin ally whose ouster led to the Russia's intervention in Ukraine.
The New York Times reported on Sunday that secret ledgers showed $12.7 million in undisclosed cash payments had been designated for Manafort from the Yanukovych administration. In a statement Monday, Manafort called the report "unfounded, silly and nonsensical," and said he had never taken an "off-the-books cash payment" nor worked for the governments of Ukraine or Russia.
On Thursday, The Associated Press reported that emails it obtained show that a firm run by Manafort orchestrated a covert Washington lobbying operation on behalf of Yanukovych's party to influence American public opinion between 2012 and 2014. Manafort did not comment when reached by the AP on Thursday, the news organization said.
Manafort joined the campaign in March and had clashed with campaign manager Corey Lewandowski, who was fired three months later.
Lewandowski had advocated a "Let Trump be Trump" strategy, while Manafort, a veteran of Republican politics, had tried to get the New York tycoon to tone down his harsh rhetoric.
In a marked change in tone on Thursday, Trump told a North Carolina rally he expressed regret for remarks that "may have caused personal pain."
"Sometimes, in the heat of debate and speaking on a multitude of issues, you don't choose the right words or you say the wrong thing," he said. "I have done that, and I regret it, particularly where it may have caused personal pain. Too much is at stake for us to be consumed with these issues."
Less than three months before the election, Clinton is leading Trump by 47 percent to 41 percent, according to the Real Clear Politics' average of data from major polling operations.
Trump and running mate Mike Pence were in Louisiana on Friday, surveying damage from deadly floods that have displaced tens of thousands of people. In an editorial Wednesday, The Advocate newspaper in Baton Rouge called on President Barack Obama to cut short his vacation on Martha's Vineyard and visit "the most anguished state in the union."
Correction: This story was revised to correct that Manafort's title had been Trump campaign chairman.
— The Associated Press contributed to this story.