Hagel announced he was stepping down last Monday, although the move was broadly interpreted as a push from an administration looking to shift gears on foreign policy.
If confirmed, Carter will be the fourth Defense Secretary under President Obama. He served as Deputy Defense Secretary under both Hagel and his predecessor, Leon Panetta. He was also the Pentagon's chief weapons buyer under Obama's first Secretary of Defense Robert Gates.
Before settling on Carter, Obama reportedly considered former undersecretary of defense Michèle Flournoy and Sen. Jack Reed, D-R.I., both whom removed themselves from consideration. He also eyed current Secretary of Homeland Security Jeh Johnson, but opted against promoting one member of his Cabinet only to face another tough confirmation in the Senate.
Hagel's resignation was the latest in a series of high-profile turnovers this year: The current Health and Human Services Secretary Sylvia Mathews Burwell, Housing and Urban Development Secretary Julian Castro, and Veterans Affairs Secretary Robert McDonald, as well as the chief of the White House Office of Management and Budget Shaun Donovan and the White House press secretary Josh Earnest are all new in their jobs this year. Attorney General Eric Holder has also announced his intention to resign, and President Obama has nominated U.S. Attorney for Eastern New York Loretta Lynch to replace him.