Paul Manafort has resigned as Donald Trump’s campaign chairman.

The move came Friday, several days after the Republican nominee restructured his leadership team.

“This morning Paul Manafort offered, and I accepted, his resignation from the campaign,” Trump said in a statement. “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. Paul is a true professional and I wish him the greatest success.”

Manafort’s work for pro-Russian Ukrainian politician Viktor Yanukovych, who fled to Russia after he was ousted in 2014, has been the subject of an onslaught of press scrutiny. Recent reports have scrutinized Manafort’s business ties to Russian and Ukrainian oligarchs. The Associated Press reported on Thursday that a firm run by Manafort and an aide orchestrated a pro-Yanukovych lobbying campaign, but did not register as foreign agents.

On Wednesday, Trump named Kellyanne Conway as his campaign manager and Steve Bannon as CEO.

Manafort was named to Trump’s campaign in March, and his appointment quickly ignited speculation over the role of then-campaign manager Corey Lewandowski, with reports that the two clashed. Lewandowski departed in June, and tweeted out earlier this week a New York Times story on Manafort’s business dealings in Russia and Ukraine.