ERIC BARADAT via Getty Images "Acting Secretary Shanahan stated that he supported an investigation into these allegations. We have informed him that we have opened this investigation,” a Pentagon spokesman told CNN.

The Politico report prompted the government watchdog group Citizens for Responsibility and Ethics in Washington to file a complaint with the Pentagon’s inspector general earlier this month. The group said it worried Shanahan had violated ethics rules, saying any favoritism toward Boeing could be a use of his public office for private gain. “Federal law prohibits Acting Secretary Shanahan from using his office for the private gain of others,” the group said. “Government resources should be used for public purposes, not to promote or denigrate any private business.” Shanahan has denied any wrongdoing and told lawmakers last week he would support an investigation into his conduct. “In his recent Senate Armed Services Committee testimony, Acting Secretary Shanahan stated that he supported an investigation into these allegations. We have informed him that we have opened this investigation,” a Pentagon spokesman told CNN. The probe could impede any effort to make him the permanent defense secretary. The New York Times noted that some Pentagon officials believed Trump was prepared to nominate him for the job, but it’s unclear if he’d have enough support in the Senate to be confirmed. The federal government is still dealing with the fallout from two airline accidents involving Boeing’s 737 Max jetliners, most recently a crash in Ethiopia that left 157 people dead. The Federal Aviation Administration is under scrutiny over the safety analysis of the planes, which reportedly had crucial flaws, according to an investigation by The Seattle Times. Transportation Secretary Elaine Chao this week called on the agency to open an inquiry into the review process of the 737 Max.