Tennessee Sen. Mark Green, R-Clarksville, is President Donald Trump's pick to be U.S. Secretary of the Army, according to a source familiar with the president's selection.

The move means Green will vacate his Senate seat and abandon a 2018 run for governor of Tennessee.

A formal announcement has not been made, but one is expected soon.

Green, a former Army officer and West Point graduate who is popular among many tea party-aligned Republicans, could not be reached for comment Saturday.

The Tennessean first reported Green as a top finalist for the position last month, and some expected an announcement when Trump visited Nashville for a rally in March. Green spoke at the Municipal Auditorium event with other lawmakers and leaders, but no announcement was made. His remarks referenced additional funding and resources Trump has suggested he wants to provide to the military.

The Secretary of the Army, which is the top civilian leader for the U.S. Army, has oversight of the 140-plus Army reserve installations worldwide and an approximately $150 billion budget.

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Green has been going through standard background checks, another source close to the search said.

The White House's selection of Green, a Clarksville Republican and West Point graduate, comes after Vincent Viola, Trump's previous nominee for the position, withdrew his nomination last month.

Viola, a billionaire and owner of the Florida Panthers NHL team, withdrew his nomination for the position after he said he couldn’t separate himself from his businesses enough so as not to pose a conflict of interest.

Green, a 52-year-old physician, was deployed three times overseas during his military service. He was an Army medic for a special operations team that captured Saddam Hussein and wrote a book about the experience. Green, like Viola, attended the United States Military Academy.

After his Army career, Green founded AlignMD, an emergency room management firm, which was acquired by American Physician Partners in 2016 as part of a $24 million deal.

Green will need to get Senate confirmation to make his appointment official.

An appointment of Green would considerably shake up the governor’s race in Tennessee. Green, who draws from a base on the far right, was the first to formally enter the 2018 Republican gubernatorial primary that is expected to attract several candidates. Randy Boyd, former commissioner of the Tennessee Department of Economic and Community Development, announced his bid last week.

Other possible Republican candidates include U.S. Rep. Diane Black, Franklin businessman Bill Lee, House Speaker Beth Harwell, Senate Majority Leader Mark Norris and former state lawmaker Joe Carr.

After speculation of Green's appointment, fellow Sen. Mae Beavers, R-Lebanon, said she was considering joining the crowded field of Republican candidates for governor.

Green was first elected to the Senate in 2012, beating incumbent Democrat Tim Barnes, who is now an elected judge in Montgomery County. The District 22 seat had been long held by Democrats until moving to the Republican column like much of the state in recent election cycles. Democrat Rosalind Kurita held the seat before Barnes.

Reach Joey Garrison at 615-259-8236 and on Twitter @joeygarrison.

This story originally appeared on The Tennessean’s website.