A 2010 investigation by the U.S. Army's inspector general concluded that lieutenant governor and senatorial candidate John Walsh used his position as Montana adjutant general for private gain.
The report also says Walsh improperly used government resources and improperly endorsed a non-federal entity.
Lee Newspapers of Montana reports the investigation followed complaints by troops who said Walsh coerced them to pay dues to join the National Guard Association of the United States.
Walsh was on the board of the private group and was running for a leadership post.
Walsh says he disagreed with the conclusion of the investigation. He was not disciplined.
Former Gov. Brian Schweitzer says he threw away the report and called it "much ado about nothing."
Walsh is running for the Senate seat being vacated by Sen. Max Baucus.