President Trump said on Twitter Saturday that Interior Secretary Ryan Zinke will be leaving the Trump administration at the end of the year.

"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," he tweeted. "Ryan has accomplished much during his tenure and I want to thank him for his service to our Nation."

"The Trump Administration will be announcing the new Secretary of the Interior next week," he added.

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Zinke's tenure at the Interior Department was marred by several investigations by the Interior Department Office of the Inspector General and the Justice Department. His actions as secretary would have been easy fodder for investigations by House Democrats set to take the majority in 2019. In November, Zinke criticized Rep. Raul Grijalva, the Democrat who would oversee any probes into Zinke's management, saying it would be hard for Grijalva to "think straight from the bottom of a bottle."

In a statement posted to Twitter Saturday afternoon, Zinke alluded to these investigations, saying that he could not "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," Zinke said.

He was scrutinized in 2017 after a tiny Montana company in his hometown was awarded a $300 million contract to help restore Puerto Rico's power grid, although Zinke denied that he was involved in the decision to provide the contract.

Zinke was investigated and cleared by the inspector general of wrongdoing following a complaint that he redrew the boundaries of a national monument in Utah to benefit a state lawmaker and political ally. Internal investigators also were reviewing Zinke's decision to block two tribes from opening a casino in Connecticut and a complaint that he reassigned a former Interior official in retaliation for criticizing Zinke. They also filed a report finding that taxpayers spent $25,000 on security for his vacation to Turkey and Greece with his wife.

Zinke was under scrutiny in October after Housing and Urban Development Secretary Ben Carson told his staff that HUD's assistant secretary for administration, Suzanne Tufts, was leaving to become the new DOI inspector general, effectively replacing Mary Kendall, the top DOI inspector general official overseeing multiple investigations into Zinke. (The agency hasn't had a permanent inspector general in years.)

But Heather Swift, a senior adviser to Zinke, dismissed reports that Tufts would be replacing the current deputy inspector general as "jumping to conclusions." No decision was ultimately made to move Tufts to the Interior Department, and HUD sent out an email with "false information" in it, Swift said.

The OIG also sent one of its inquiries to the Justice Department for investigation at the end of October.

Zinke also made waves last month for blaming "environmental radicals" for deadly wildfires in the state, saying after he toured the damage from the Camp Fire that environmentalists stop forest management practices that could have prevented the fires.