Donald Trump announced the departure of another member of his Cabinet, Ryan Zinke, the latest in a series of high profile departures from his administration.
As interior secretary Mr Zinke, 51, a former Navy SEAL from Montana, wore cowboy boots to the office.
He spearheaded a rolling back of environmental regulations, and an expansion of oil and gas drilling, but was facing a host of ethics investigations relating to business dealings.
Mr Zinke said he would be leaving his post at the end of the year.
Mr Trump, writing on Twitter, said: "Secretary of the Interior Ryan Zinke 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."
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
The interior secretary oversees public land in America, which covers an area larger than the whole of Mexico.
Mr Zinke had become a lightning rod for complaints from Democrats, and was expected to be the target of investigations when Democrats take over control of the House of Representatives in January.
Chuck Schumer, the Democrat leader in the US Senate, said: "Ryan Zinke was one of the most toxic members of the cabinet in the way he treated our environment, our precious public lands, and the way he treated the government like it was his personal honey pot. The swamp cabinet will be a little less foul without him."
Mr Zinke, a former Montana congressman, already faced investigations linked to property holdings in his home state.
He had also come under fire over expenditure in office, including reports that his department was spending nearly $139,000 to upgrade three sets of double doors in his office. Mr Zinke later said he negotiated the cost down to $75,000.
He was also reportedly the subject of investigations over allegations he allowed his wife to ride in government vehicles, that he took a security detail with him on holiday to Turkey, and costly flights on US Park Police helicopters.