President Trump announced Friday via Twitter that Interior Secretary Ryan Zinke will step down from his post in the coming weeks. Zinke has headed the Department of the Interior (DOI) since 2017 and overseen some of the more significant rollbacks in environmental policy in the US.

Trump said a successor to Zinke would be named in the coming week . Reuters speculates current Interior Deputy Secretary and former oil, gas, and water industry lobbyist David Bernhardt is a likely candidate for the job. According to Politico, Bernhardt played an active role in weakening endangered species protections to make it easier for oil and gas drilling to occur on ecologically sensitive land.

Zinke's time in office was marked by a similar effort to stymie the environmental protections put in place by the Obama administration in the name of oil and gas interests. In one of his most controversial moves, Zinke reopened vast tracts of federal waters that had previously been off-limits to offshore oil and gas drilling. The secretary drew sharp criticism for opening up federal waters adjacent to states that didn't want offshore drilling, while exempting Florida from the same treatment after a meeting from the state's Republican governor.

Zinke also helped reduce the size of certain national monuments to accommodate more oil and gas drilling. At a time when fighting climate change is more urgent than ever, the Secretary did nothing to address the fact that nearly a quarter of the US' carbon emissions come from the life cycle of drilling and mining on public lands.

That said, Zinke didn't always toe the line when it came to policies that favored oil and gas. Zinke rejected a recommendation from an Interior Department panel that asked him to lower the royalties that oil, gas, and coal companies pay back to the federal government when they drill or mine on federal land. Zinke also cleared the way for offshore wind development on some Atlantic coast federal waters.

In recent months, Zinke has faced a number of investigations on improper spending and would likely face more scrutiny under a Democratic-majority House, according to E&E News.

Zinke alluded to this in a statement on Friday, saying, "After 30 years of public service, I cannot justify spending thousands of dollars defending myself and my family against false allegations. It is better for the President and Interior to focus on accomplishments rather than fictitious allegations."

One of these ongoing investigations involves a land deal in Montana, in which a parcel owned by Zinke and a parcel of a park established by Zinke in 2007 were approved for commercialization with the backing of Halliburton Chairman David Lesar, which conducts oil and gas work overseen by the Interior Department. Zinke and Lesar apparently met at Interior Department Headquarters about the deal in 2017, raising suspicions that conflict-of-interest rules were broken. Another investigation of Zinke is probing whether political influence led him to improperly block a Connecticut tribe from opening a casino.