Still, some Democrats called for answers to what he knew about the leak cases.
New York Senator Chuck Schumer, the majority leader, urged Mr. Demers on Sunday to testify in front of Congress.
When Mr. Demers became head of the National Security Division on February 22, 2018, he received praise from both Democrats and Republicans who found he had worked under administrations from both parties.
The confirmation is his third assignment in the department. From 2006, when the National Security Division was created, until 2009, Mr. Demers was part of its leadership team. He previously served in the department’s Office of Legal Counsel, essentially the government’s chief legal advisor, and in the office of the Assistant Attorney General.
He graduated from Harvard Law School, where he and Mr. Carlin were friends and classmates.
As the head of the National Security Division, he is likely best known for his work in combating the threat of Chinese intellectual property theft and espionage.
When the White House announced Mr. Olsen’s nomination to take over the department, Mr. Demers said in an email to his staff that “Matt is the right person to head this department,” according to a copy The Times received Has.
Prior to joining Uber, Mr. Olsen served as a federal attorney in the U.S. Attorney’s Office in Washington and held senior positions at the F.B.I. and the National Security Agency and as director of the National Counterterrorism Center during the Obama administration.
Mr. Lesko has served as U.S. Assistant Attorney for the Eastern District of New York since March, replacing Seth DuCharme. Mr Lesko was the district prosecutor from 2002 to 2009 and returned to the office in 2018.
Nicole Hong Reporting from New York contributed.