Just months after Paul Manafort was promoted to bring some structure to and scale up Donald Trump's presidential bid, the Washington insider has resigned from the campaign.

In a statement Friday morning, Trump said that Manafort offered his resignation. The candidate said he is "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," Trump continued.

Manafort had been leading the campaign as chairman, but his resignation comes just days after a shakeup at the top of the operation. Trump hired two new top campaign officials, widely seen as a demotion for Manafort.

After the staff change, The New York Times reported that Manafort wrote in an internal staff memo: "This is an exciting day for Team Trump. I remain the campaign chairman and chief strategist, providing the big-picture, long-range campaign vision."

Stephen Bannon of Breitbart News is now serving as chief executive of the campaign and pollster Kellyanne Conway is campaign manager.

Manafort was under scrutiny earlier this week after The New York Times reported that his name appeared in a "black ledger" of off-the-book payments made by former Ukrainian President Viktor Yanukovych's party.

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