Secretary of the Interior Ryan Zinke will leave his job in the administration at the end of the year, President Donald Trump announced in a tweet on Saturday morning.

The president said in a followup tweet that the White House would announce a replacement next week. Trump chose Zinke in December 2016 to serve in the cabinet-level position.

"[Zinke] has accomplished much during his tenure and I want to thank him for his service to our Nation," the president tweeted.

Zinke, a former Navy SEAL and Montana's lone congressman, will leave a legacy as a secretary who rolled back federal lands protections in pursuit of the Trump agenda to increase energy production.

Secretary of the Interior Ryan Zinke arrives at the U.S. Capitol on Dec. 3, 2018. Shawn Thew / Getty Images file

The Interior Department oversees management of about three-quarters of federal land and natural resources, along with programs relating to American Indian and territorial affairs.

Multiple progressive and environmental organizations said in statements that they were glad to see Zinke go, as he was seen as a friend to fossil-fuel corporations.

“Zinke will go down as the worst Interior secretary in history,” said Kieran Suckling, executive director of the Center for Biological Diversity. “His slash-and-burn approach was absolutely destructive for public lands and wildlife."

Zinke was also accused of profiting from his current position, and the heat on the former congressman increased in recent weeks after the Democrats took control of the House of Representatives, gaining subpoena power.

A Democratic source on Capitol Hill and another at the Interior Department said pressure on Zinke was significant, especially with two outstanding Inspector General investigations: the Halliburton deal and another on a Connecticut casino involving MGM.

As incoming chairman of the House Natural Resources Committee, Rep. Raul Griljalva, D-Ariz., already promised that he planned to force Zinke to testify before the committee over a profitable land deal between his family and Halliburton chairman David Lesar in the secretary's hometown of Whitefish, Montana.

The concern was over a conflict of interest between Zinke's position and the Halliburton corporation, which could benefit from the Interior Department's decisions on energy production.

A Democratic source on Capitol Hill and another at the Interior Department said pressure on Zinke was significant, especially with two outstanding Inspector General investigations — the Halliburton deal and another involving a Connecticut casino and MGM.

A House Democratic source says Zinke was facing aggressive upcoming oversight from Democrats in the form of multiple hearings and investigations once they take over the House of Representatives in January.

In a USA Today op-ed published Nov. 30, Griljalva called for Zinke to resign immediately, citing some 17 investigations into the secretary and his department. The land deal in Whitefish was recently referred to the Justice Department.

Griljalva said that he planned to investigate Zinke and would also fulfill his role of providing oversight of anyone who replaced Zinke.

“Doing whatever you like and then leaving office a half-step ahead of a formal investigation is not public service, especially if you end up working for an industry you formerly regulated,” Griljalva wrote. “The election results were about clean government as much as any particular policy choice, and the next Interior secretary will be watched as closely as the one before.”

Zinke responded to the congressman in a caustic statement that took aim at Griljalva personally — a counter-punch, rather than a defense.

“It’s hard for him to think straight from the bottom of the bottle,” Zinke wrote in a statement he posted to Twitter. "This is coming from a man who used nearly $50,000 in tax dollars as hush money to cover up his drunken and hostile behavior. He should resign and pay back the taxpayer for the hush money and the tens of thousands of dollars he forced my department to spend investigating unfounded allegations."

Grijalva did pay a former staffer more than $48,000 after she accused him of being drunk and creating a hostile work environment, according to The Arizona Republic. Grijalva admitted to having a drinking problem, but said he had since gotten it under control.

Progressive groups, meanwhile, signaled that they were wary at the possibility of Zinke's deputy replacing him as secretary.

David Bernhardt currently serves as deputy secretary of the interior and is considered a candidate for promotion. He is a former lobbyist "whose list of former clients reads like a 'who's who' of oil companies and anti-conservation interests," according to a Center for American Progress statement.

"Bernhardt has been quietly working to weaken the Endangered Species Act, speed drilling for oil in the Arctic Refuge, and delivering favors for his former clients," the liberal advocacy group said. "Given his vast conflicts, it is impossible for Bernhardt to effectively and ethically lead the Interior Department, and he should not be allowed to serve as acting secretary — let alone be nominated to the position."