Unable to get either Alaska senator to spill the beans about allegations that a member of President Trump’s cabinet threatened funding to their state in order to secure their votes on a bill to repeal the Affordable Care Act, a government watchdog is closing his investigation into the matter.

As the White House scrambled unsuccessfully in July to whip the votes for the health care repeal bill, Interior Secretary Ryan Zinke allegedly called both of Alaska’s Republican senators—Lisa Murkowski and Dan Sullivan—and communicated a “troubling message” about future federal dollars for their state if they didn’t fall in line.

The ham-handed gambit backfired spectacularly. Murkowski, who chairs the committee that controls the Interior Department’s budget and confirmation process, defiantly voted against the Obamacare repeal bill, noting that she is “strong and independent” and would not bow to intimidation.

Though Murkowski and Zinke later made a show of making amends over a beer, other members of Congress found the episode disturbing, and demanded a federal inquiry.

In a letter on Wednesday to the two House Democrats who demanded the probe, however, the Interior Department’s inspector general said that “further investigation would be unproductive.”

“Both Senators Murkowski and Sullivan declined to be interviewed or to provide statements regarding the matter,” Deputy Inspector General Mary Kendall wrote. “The OIG does not believe that it could meaningfully investigate the matter further.”