Trump tweets that Zinke "accomplished much during his tenure" and that a replacement would be announced next week. The Cabinet post requires Senate confirmation.
Zinke, a 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.
Secretary of the Interior @RyanZinke will be leaving the Administration at the end of the year after having served for a period of almost two years. Ryan has accomplished much during his tenure and I want to thank him for his service to our Nation.......— Donald J. Trump (@realDonaldTrump) December 15, 2018
Zinke played a leading part in Trump's efforts to roll back environmental regulations and promote domestic energy development.
His departure comes amid a staff shake-up as Trump heads into his third year in office. The president on Friday named budget director Mick Mulvaney as chief of staff.