WASHINGTON (AP) — The Pentagon’s watchdog agency on Thursday cleared Acting Defense Secretary Patrick Shanahan of wrongdoing in connection with allegations that he had used his official position to favor his former employer, Boeing Co.

The decision by the Defense Department inspector general appears to open the door for President Donald Trump to nominate Shanahan to succeed Jim Mattis as defense secretary. The White House, however, has not said whether Trump intends to do so. Shanahan is not thought to face any organized opposition to Senate confirmation, although his career service in the defense industry and limited government experience could be issues.

After Mattis quit last December in protest of Trump’s policies, the president installed Shanahan as acting secretary but did not nominate him. Although he has publicly praised Shanahan’s work, Trump has seemed content letting him remain in limbo, as he has with a number of other Cabinet-level officials and others.

“I like acting. It gives me more flexibility,” Trump said in January.

Shanahan, who spent 31 years at Boeing, has been serving as the interim Pentagon chief since Jan. 1, after Mattis resigned. The allegations of bias toward Boeing stemmed from his 18 months as deputy defense secretary, beginning in July 2017.

In a written statement summarizing the outcome of its probe, which began on March 15, the inspector general’s office said it “did not substantiate any of the allegations and determined that Acting Secretary Shanahan fully complied with his ethical obligations and agreements regarding Boeing and its competitors.”

Glenn Fine, the interim inspector general, issued a separate statement saying the probe had been conducted “fairly, thoroughly and expeditiously.”