The Interior Department acknowledged Secretary Ryan Zinke phoned Senate Energy Chairwoman Lisa Murkowski and Sen. Dan Sullivan one day after Murkowski voted against the GOP's legislation to repeal the Affordable Care Act. | Jacquelyn Martin/AP Photo Watchdog closes Zinke threat probe, citing lack of cooperation from Interior

The GAO said today it couldn't issue an opinion on whether Interior Secretary Ryan Zinke violated the law by reportedly threatening an Alaskan senator in a phone call because the agency didn't cooperate in its probe.

Interior acknowledged Zinke phoned Senate Energy Chairwoman Lisa Murkowski (R-Alaska) and Sen. Dan Sullivan (R-Alaska) one day after Murkowski voted against the GOP's legislation to repeal the Affordable Care Act. But it didn't speak to allegations that Zinke warned of negative consequences to energy and public lands policy in the state due to that vote.


Federal law generally allows "agency officials to voice their position on matters of public policy by direct appeals to Congress," but Interior's lack of cooperation prevented investigators from determining whether any lines were crossed, according to a letter from Thomas Armstrong, GAO's general counsel, to the two senior House Democrats who requested the probe last July.

"Interior did not provide us with any information on the substance of the telephone calls. In light of this, we lack the requisite facts on which to base a legal opinion," Armstrong wrote.

New Jersey Rep. Frank Pallone, top Democrat on the Energy and Commerce Committee, and Arizona Rep. Raúl Grijalva, top Democrat on the Natural Resources Committee, said the lack of cooperation underscored the need for congressional oversight.

"Secretary Zinke seems to think he can threaten anyone he wants as long as Republicans cover for him," Grijalva said in a statement.