US Interior Secretary Ryan Zinke is set to leave his role at the end of the year, according to president Donald Trump.
Mr Trump tweeted that Mr Zinke “accomplished much during his tenure” and that a replacement would be announced next week.
The cabinet post requires Senate confirmation.
Mr Zinke is currently facing federal investigations into his travel, political activity and conflicts of interest.
The former Republican congressman from Montana, is leaving weeks before Democrats take control of the House, a shift in power that promised to intensify probes into his conduct.
Mr Zinke played a leading part in President Trump's efforts to roll back environmental regulations and promote domestic energy development.
His departure comes amid a staff shake-up as President Trump heads into his third year in office.
The president on Friday named budget director Mick Mulvaney as chief of staff.
Additional reporting by AP.
