WASHINGTON – President Donald Trump made it official Monday and nominated Mark Esper to be the next secretary of defense.

As part of an expedited confirmation process, the Senate Armed Services Committee will hold a confirmation hearing for Esper on Tuesday.

Esper has been acting secretary of defense since Patrick Shanahan, the previous acting secretary, stepped down last month after USA TODAY and others revealed details of his turbulent divorce and family life. Trump announced shortly afterward that he planned to nominate Esper to be permanent defense chief but had not made it official.

The Pentagon has been without a Senate-confirmed defense secretary since Jim Mattis resigned in December – the longest stretch in history.

“We need Senate-confirmed leadership at the Pentagon, and quickly,” Sen. James Inhofe, R-Okla., chairman of the Armed Services committee, said when announcing Esper's hearing last week. He said the hearing will "give committee members the chance to ask questions… and learn more about how he will work to lead the Pentagon, advocate for service members, support the National Defense Strategy and keep American families safe.”

Who is Mark Esper:Here is what you need to know about him.

He and the top Democrat on the committee, Sen. Jack Reed, D-R.I., cautioned that even though they agreed to speed up the process, Esper's confirmation is not guaranteed.

“(T)here are no shortcuts and this nominee, like every nominee to this critical post, must be thoroughly vetted and carefully evaluated,” Reed said. The committee typically waits at least a week after receiving a nomination before holding a hearing.

“Both Chairman Inhofe and I agree the United States needs a permanent Secretary of Defense,” he said.

Esper, a former defense industry lobbyist, has gone through the Senate confirmation process before. The Senate confirmed his nomination to be army secretary in 2017 by a vote of 89-6.

Esper has a masters’ degree in public administration from Harvard University and a doctorate in public policy from George Washington University, according to his official biography.

He served in the Army after graduating from the U.S. Military Academy at West Point in 1986. Commissioned as an infantryman, he served during the 1990-1991 Gulf War and received a Bronze Star, among other commendations.

He has worked at the Pentagon before, including as a deputy assistant secretary of defense for negotiations policy during the administration of George W. Bush. He has also worked on Capitol Hill, where he did stints as a national security adviser to former majority leader Sen. Bill Frist, R-Tenn., and as a staff member of the Senate Foreign Relations and House Armed Services committees.

Before being sworn in as army secretary in 2017, he spent several years as the top lobbyist for Raytheon.

During his confirmation process, Esper is required give up the acting secretary's duties and go back to his post as army secretary. Federal law prohibits him from being acting secretary at the same time he is seeking Senate confirmation of his nomination.

Navy Secretary Richard Spencer is stepping in to become acting defense secretary in the meantime, Pentagon officials said. They said he took over shortly after 3 p.m. Monday, when the Senate received Esper's nomination

Who's Mark Esper:He's the nominee for Defense Secretary. Here is what you need to know about him.

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