WASHINGTON — Acting Secretary of Defense Patrick Shanahan on Tuesday removed himself from consideration as the next secretary of defense and resigned from his post as acting defense secretary. The news came shortly after USA Today reported the FBI was investigating a domestic dispute from nine years ago between ​Shanahan and his former wife.

Shanahan “has decided not to go forward with his confirmation process so that he can devote more time to his family,” President Trump tweeted on Tuesday.

Trump on May 9 announced he intended to nominate Shanahan to run the Pentagon. Shanahan joined the administration in April 2017 as deputy defense secretary after a 30-year career at Boeing. He became acting secretary in January following the resignation of Jim Mattis.

In a statement, Shanahan said: “It has been a deep honor and privilege to serve our country alongside the men and women of the Department of Defense. I am proud of the work accomplished over the last two years. … We are developing capabilities that will ensure American military leadership for decades to come in space, cyber, hypersonic missiles, and much more.”

After being confirmed as deputy secretary less than two years ago, said Shanahan, “it is unfortunate that a painful and deeply personal family situation from long ago is being dredged up … I would welcome the opportunity to be Secretary of Defense, but not at the expense of being a good father.”

Shanahan was the longest-serving acting secretary of defense in history, holding that position for 182 days.

In November 2017, Shanahan was suddenly thrust into the role of principal space adviser to then Secretary Mattis after Congress in the 2018 National Defense Authorization Act stripped that job from Air Force Secretary Heather Wilson, reassigned it to Shanahan and directed him to study ways to reorganize the DoD space enterprise. After Trump in June 2018 directed DoD to stand up a Space Force as a separate military service, Shanahan led the push to write a legislative proposal and persuade lawmakers to authorize the new branch.

Trump on Tuesday named Army Secretary Mark Esper acting defense secretary.

Rep. Mac Thornberry (R-TX), Ranking Member of the House Armed Services Committee, called on the White House and the Senate to get a permanent secretary of defense as quickly as possible.

“However well-qualified Secretary Esper may be, it is critical that the President nominate, and that the Senate confirm, a permanent Secretary of Defense,” said Thornberry. “This job should be filled in a matter of a few weeks, not months. The uncertainty surrounding this vacant office encourages our enemies and unsettles our allies.”

If Esper gets the nomination, his background as a former Raytheon executive is likely to come under scrutiny.

“In Patrick Shanahan, President Trump had an acting Secretary of Defense whose decisions were overshadowed by his previous senior position at Boeing. His successor will likewise risk being tainted by his previous work for a major defense contractor,” Citizens for Responsibility and Ethics in Washington executive director Noah Bookbinder said in a statement.

Bookbinder noted that Esper as acting secretary of defense he will have potential influence over the controversial proposed merger of Raytheon and United Technologies to become the second largest defense company in the United States.

His ethics agreement—and his ability to follow it—will be something we will be watching closely.”

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...