Mary Miller, the Treasury Department official who led implementation of new financial regulations including the Volcker rule, is leaving the department in early September.

Miller, 58, has been the undersecretary for domestic finance since 2012 and was assistant secretary for financial markets for two years before that. A successor would have to be nominated by President Obama and confirmed by the Senate.

Miller is leaving to give a successor more than two years in the position before Obama's term ends in January 2017, according to a person with knowledge of the matter. The Treasury hasn't named anyone to replace her on an interim basis once she leaves.

"For over four years, Mary has worked tirelessly on behalf of the American people, leading our department's efforts to tackle some of the most difficult challenges facing our country," Treasury Secretary Jacob J. Lew said in a statement today.

Lew also cited Miller's role overseeing Treasury debt, especially during the administration's debates with Congress over raising the federal borrowing limit in 2011 and last year.

Miller spent 26 years at Baltimore-based asset manager T. Rowe Price Group Inc. as director of fixed income, head of the municipal bond department and a portfolio manager. She led a public conference last month at the Treasury on whether asset managers pose a potential threat to financial stability and should be designated systemically important by a council of U.S. regulators.

Miller also coordinated five U.S. agencies that wrote the Volcker rule intended to limit risks from proprietary trading at banks. The rule, which regulators worked on for more than three years, was completed in December.

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