WASHINGTON (Reuters) - U.S. banking rules must protect the financial system but they need “some refinement,” President Donald Trump’s nominee for the Federal Reserve’s top regulatory post told lawmakers on Wednesday.

“As with any complex undertaking, after the first wave of reform, and with the benefit of experience and reflection, some refinements will undoubtedly be in order,” Randal Quarles told the Senate Banking Committee in prepared testimony ahead of his confirmation hearing scheduled for Thursday.

If confirmed by the Senate, Quarles will be the central bank’s top official tasked with protecting the stability of the financial system.

Quarles worked as a Wall Street lawyer and U.S. Treasury official under President George W. Bush. He was also an executive with private-equity firm Carlyle Group LP (CG.O) and is expected to face tough questions from Democratic lawmakers.

Republicans control the Senate and have the votes to confirm Quarles over any objections from Democrats.

If confirmed, Quarles would step down from the Cynosure Group, an investment group he founded in 2014.