WASHINGTON (Reuters) - A leading Democratic lawmaker on Thursday said he would ask federal officials to investigate reported threats by Interior Secretary Ryan Zinke regarding Alaska energy policy to retaliate against opposition from one of the state’s Republican senators to efforts to repeal Obamacare.

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U.S. Representative Raul Grijalva of Arizona, the top Democrat on the House of Representatives’ Committee on Natural Resources, said an investigation is necessary and called Zinke’s actions unethical.

The congressman will ask the Government Accountability Office, the Interior Department’s inspector general or both to investigate, a spokesman said.

The Alaska Dispatch News on Thursday reported that Zinke had called Senators Lisa Murkowski and Dan Sullivan, both Republicans, on Wednesday. He warned them that Murkowski’s vote on Tuesday against a motion to begin debate on the healthcare overhaul could have negative consequences for energy and land use in Alaska, the newspaper said. Murkowski’s no vote forced Vice President Mike Pence to cast a tie-breaking vote to pass the motion by a 51-50 ballot.

The call from Zinke followed a phone conversation Murkowski had with Republican President Donald Trump on Tuesday, which she described to E&E News, an energy and environment publication, as “very unpleasant.”

Murkowski spokeswoman Karina Petersen confirmed that Zinke had called the senator.

“Threatening to punish your rivals as political blackmail is something we’d see from the Kremlin,” Grijalva said. “Secretary Zinke’s willingness to deliver these threats speaks volumes about his ethical standards and demonstrates that Interior’s policy positions are up for political grabs, rather than based on science or the public interest.”

Zinke’s office did not respond to requests for comment.

His Interior Department oversees more than 20 percent of federal land, including national parks such as Yosemite, and deals with energy development on public land and offshore areas. The department deals with policies crucial to Alaska’s economy such as oil drilling and control of wildlife areas. Until he became a Cabinet member earlier this year, he was himself a U.S. congressman, representing Montana.

Murkowski, as chair of the Senate Committee on Energy and Natural Resources, oversees appropriations and appointee confirmations for the Interior Department.

Separately, Interior Department watchdog group the Western Values Project filed a records request related to Zinke’s calls to Murkowski and Sullivan.