The White House announced Tuesday that the president would nominate the Pentagon’s head of weapons acquisition to be the agency’s No. 2 official.

In selecting Ashton B. Carter to be deputy secretary of defense, the White House signaled the importance it places on finding savings and cuts in the Defense Department’s budget.

Carter, if confirmed, would take over from William J. Lynn III, who announced his resignation last month. The Senate is expected to confirm Carter with little opposition.

The deputy defense secretary has traditionally worked behind the scenes, overseeing the Pentagon’s vast bureaucracy. Carter’s tenure probably will be consumed by a need to begin cutting hundreds of billions of dollars from the military’s budget over the next decade. The Pentagon faces cuts estimated up to $1 trillion.

Carter has long been seen as the front-runner for the job, along with Michele A. Flournoy, the undersecretary of defense for policy. The spiraling deficit and the need for big cuts to the Pentagon budget appear to have made Carter, who has a deep knowledge of the military’s multi-billion-dollar weapons programs, a more logical choice.

Carter, who received a doctorate in theoretical physics from Oxford University, has taught at Harvard and served in the Pentagon during the Clinton administration, focusing on North Korea, nuclear arms issues and terrorism.