President Biden is nominating Gen. Charles “C.Q.” Brown Jr. to serve as the next chairman of the Joint Chiefs of Staff, the president is expected to announce Thursday in a White House Rose Garden ceremony.

Brown is currently the Air Force chief of staff. 

The position is the nation’s highest-ranking military officer, and the chairman is the primary military adviser to the president, as well as to the defense secretary and National Security Council. 

Brown would replace Gen. Mark Milley, who was appointed by then-President Donald Trump in 2019. The chairman serves at the pleasure of the president for a four-year term. Milley held the job during the Jan. 6, 2021, assault on the Capitol and the deadly withdrawal of U.S. troops from Afghanistan. 

Milley’s term ends in September, but it is customary for the president to select a successor in the spring to allow time for congressional confirmation. Defense Secretary Lloyd Austin recommended Brown. 

But Brown’s confirmation could be delayed because Republican Sen. Tommy Tuberville has been blocking the Senate confirmation of hundreds of senior military promotions in order to protest the Pentagon’s policy on abortion-related travel for service members. 

If ultimately confirmed, Brown would be the first Black chairman of the Joint Chiefs of Staff since Gen. Colin Powell was tapped by President George H.W. Bush in 1989. 

With Austin as the first Black defense secretary, the selection of Brown would mark the first time ever two Black Americans held the most senior positions at the Pentagon concurrently. 

As the chief of staff of the Air Force, Brown is already a member of the Joint Chiefs of Staff. He currently oversees the training and equipping of nearly 700,000 active-duty, Reserve, Guard and civilian forces both in the U.S. and abroad. 

According to his Pentagon biography, Brown began his military service as a command pilot, with more than 3,000 flying hours, including 130 combat hours. He holds a bachelor’s degree in civil engineering from Texas Tech University. Before serving as chief of staff of the Air Force, Brown was the commander of Pacific Air Forces for the U.S. Indo-Pacific command. 

The White House says Brown has been a strong contributor to the United States’ efforts to equip Ukraine with the capabilities it needs to fend off Russia’s aggression, and says he is deeply versed in the threats posed by China. 

Mr. Biden interviewed both Brown and the commandant of the Marine Corps, Gen. David Berger, for the position. 

— Weijia Jiang contributed to this report.