Richard Cordray sent a letter to President Trump on Friday, declaring that he's officially done leading the federal government's controversial consumer watchdog agency once the clock strikes midnight.
In a separate letter to his staff, Cordray, who is the first-ever director of the fledgling Consumer Financial Protection Bureau, announced that chief of staff Leandra English will serve as the bureau's acting director.
A little over a week ago, Cordray had said he planned to leave his post at the end of November.
Shortly after Cordray's announcement Friday, President Trump named Office of Management and Budget Director Mick Mulvaney as the CFPB's interim director. The back-to-back moves set up a clash over who is in charge of the bureau.
In a tweet Friday night, Senator Elizabeth Warren, an architect of the consumer agency, said that under the Dodd-Frank financial reform law, the agency's deputy director assumes the role of acting director if there's a vacancy.
Related: Richard Cordray to step down as head of Consumer Financial Protection Bureau
Mulvaney, like many Republicans, has been a staunch critic of the CFPB. While serving in Congress, he voted in favor of killing the agency. He and other opponents argue the agency -- which was created in the wake of the 2008 financial crisis to keep an eye on Wall Street -- has too much power and installs unduly harsh regulations.
Mulvaney has worked alongside Trump to roll back some of the rules they have pinned as anti-business. And some Republicans have called for Cordray to be fired -- a move that would have proved troublesome for Trump since law forbids him from firing the CFPB director without cause.
The CFPB's proponents, however, say the agency plays a key role in preventing big business from preying on the little guy.
In his exit letter, Cordray said the CFPB's work is "vital" to the U.S. economy.
Related: Trump likely to tap budget director Mulvaney as interim CFPB chief
"We have returned almost $12 billion to more than 30 million consumers who had been cheated or mistreated by banks or other large financial companies," he wrote.
Cordray was appointed by President Obama and first assumed his post in 2012. His decision to leave may have less to do with political tension and more to do with a desire to run for governor of Ohio in 2018.
But his departure marks an opening for Trump to embark on a major overhaul of the agency.
--CNNMoney's Donna Borak, Jeremy Diamond and Julia Horowitz and CNN's Faith Karimi contributed to this report.
