Treasury Secretary Steven Mnuchin’s efforts to fill out the top ranks of the department were dealt a setback as a Goldman Sachs Group Inc. banker withdrew from consideration to serve as his deputy.

Jim Donovan cited personal reasons for declining President Donald Trump’s nomination to be the next deputy Treasury secretary.

“At this time I want to focus on my family, and I can no longer accept it,” Donovan said in statement on Friday. “I hope to be able to serve this administration in the future and fully support President Trump and Secretary Steven Mnuchin’s ongoing work to reform the tax system and grow the U.S. economy.”

The decision could impede Mnuchin’s effort to deliver an ambitious economic agenda including an historic tax overhaul this year, de-regulation of the financial industry and reform of the housing finance system. Donovan was an “enormous asset” in helping build Mnuchin’s team at the Treasury, Tony Sayegh, the department’s spokesman, said in an emailed statement.

Mnuchin has been in office since February with most key senior-level Treasury positions unfilled, including undersecretaries for domestic finance and international affairs. While in public forums Mnuchin often heaps praise on career Treasury staffers, he’s had to rely on counselors who don’t require Senate confirmation to step into senior positions. Counselors have more limits on their policy making powers than officials approved by Congress.

Nominees for Senate-confirmed government positions must disclose their finances and sign an ethics agreement before going through a vetting process by lawmakers.

The Trump administration has been wary of recruiting too many former Goldman Sachs alumni for higher-up positions.