WASHINGTON — President Joe Biden has picked Christine E. Wormuth to be the first woman to serve as secretary of the Army, Pentagon officials said Monday.

If approved by the Senate, Wormuth, who was the Defense Department’s top policy official at the end of the Obama administration, would take control of the largest branch of the military at a time when the armed services are wrestling with a range of challenges, including weeding out right-wing extremists from their ranks and confronting rising threats from China and Russia.

Wormuth, who was on Biden’s Pentagon transition team after the election, would join other women appointed to top Pentagon jobs, including Kathleen Hicks, the deputy defense secretary, and Kelly Magsamen, chief of staff to Defense Secretary Lloyd Austin.

The Biden administration has come under criticism for its slow pace of nominating officials to top Pentagon jobs, including high-ranking civilian positions overseeing the Army, Navy, Air Force and Marine Corps. In many cases, the service branches and other important parts of the Defense Department have been run by acting officials in the administration’s first months.

Wormuth, whose nomination was reported earlier Monday by Politico, began her government career in 1996 in the Pentagon policy office, which she eventually led from 2014 to 2016. Earlier in the Obama administration, she served as the main liaison from the White House’s National Security Council to the Pentagon on defense issues.

Wormuth has also worked in senior positions dealing with international security and defense policy at the RAND Corp. and the Center for Strategic and International Studies, two research institutions in Washington.