Acting Defense Secretary Patrick Shanahan said Thursday after he testified to the Senate Armed Services Committee he is not worried by a progressive watchdog group’s request that the Pentagon inspector general investigate whether he has acted unethically to help his former employer Boeing during his time at the Defense Department.

“I’m not worried. There’s not just a straight line — I’ve played way back from the line. And I welcome their work, it should be pretty straightforward,” he told Breitbart News in response to a question as he was leaving the hearing room.

On Wednesday, Citizens for Responsibility and Ethics in Washington (CREW) submitted a request to the Pentagon inspector general to investigate whether Shanahan promoted Boeing systems since coming to the Pentagon, based on news reports.

According to one report by Politico, Shanahan criticized Lockheed Martin’s handling of the F-35 fighter jet program, the most expensive weapons system in the Pentagon’s history. Another report by Bloomberg alleged the Air Force requested F-15X trainer jets made by Boeing after “prodding” from Shanahan, over aircraft made by Lockheed Martin.

“We don’t know whether Shanahan had direct involvement in decisions affecting Boeing, but even the appearance of bias raises serious concerns and potential ethics violations,” CREW Executive Director Noah Bookbinder said in a press release. “It is imperative that the Office of Inspector General fully investigate Shanahan’s conduct.”

Pentagon officials have refuted those reports, and say under Shanahan’s ethics agreement, he has recused himself for the duration of his service at the Pentagon from participating in matters in which Boeing is a party. Any matters are routed to one of several designated appointees, according to the agreement.

Army Lt. Col. Joe Buccino, a spokesman for Shanahan, told the Washington Post on Wednesday that Shanahan had “at all times remained committed to complying [with] his ethics agreement, which screens Boeing matters to another [Pentagon] official and ensures no potential for a conflict of interest with Boeing on any matter.”

Shanahan also told senators at the hearing on Thursday that he would support CREW’s investigation.

When asked by Sen. Richard Blumenthal (D-CT) whether he would support the investigation, Shanahan responded, “Yes, I would.”

He also told senators he has not spoken to anyone in the administration about the Boeing 737 MAX 8 aircraft, which has been grounded in the U.S. and other countries after two recent fatal crashes.

Shanahan, 56, worked for Boeing for more than 30 years before becoming deputy defense secretary in July 2017. He last served at Boeing as senior vice president of supply chain and operations, overseeing the company’s manufacturing operations.

He is known among aviation experts as a problem solver, and is credited with almost single-handedly saving Boeing’s 787 Dreamliner about a decade ago.

Shanahan appears to be the leading candidate to replace former Defense Secretary Jim Mattis, who resigned late last year. He served for 17 months as Mattis’ deputy, often sitting in for him during meetings in Washington while he was traveling abroad. He has also worked closely with Vice President Mike Pence to establish the Space Force.