WASHINGTON — Donald Trump's campaign chairman Paul Manafort is resigning from the campaign.

In a statement, Trump says Manafort offered his resignation Friday morning. Trump praised Manafort's work on the campaign and called him a "true professional."

Manafort is stepping down in the wake of a campaign shake-up, as well as revelations about his work for a pro-Russian political party in Ukraine.

The Associated Press reported Thursday that Manafort's firm orchestrated a covert Washington lobbying operation on behalf of Ukraine's then-ruling political party. Paul Manafort and his deputy, Rick Gates, never disclosed their work as foreign agents as required under federal law.

Earlier in the week, the campaign added two new top officials to the campaign in a move widely seen as a demotion for Manafort.