Mr. Garland most recently served as a federal appeals judge for the District of Columbia Circuit. He submitted a letter of resignation to the court on Wednesday, pending his swearing-in as attorney general.
But he is best known for Republicans’ refusal to consider his nomination in 2016 to serve on the Supreme Court, a political power play that ultimately allowed Mr. Trump to fill the seat.
Mr. Garland is also a longtime veteran of the Justice Department, having worked as a federal prosecutor in the U.S. attorney’s office in Washington during the George H.W. Bush administration and as a department official during the Clinton administration.
During that time, Mr. Garland led the investigation into the 1995 Oklahoma City bombing that killed 168 people, then the worst terrorist attack on U.S. soil. Mr. Garland vowed during his confirmation hearing, weeks after the riot at the Capitol by a pro-Trump mob, to use the full force of the department to combat domestic extremism.
Mr. Garland spent the bulk of Thursday in private briefings with top department officials, including with Christopher A. Wray, the F.B.I. director; John P. Carlin, the acting deputy attorney general; John C. Demers, the head of the national security division; and Michael R. Sherwin, the federal prosecutor overseeing the department’s sprawling investigation into the assault on the Capitol on Jan. 6.
In an afternoon visit to the U.S. attorney’s office in Washington, Mr. Garland thanked several officials in person for their work on the investigation, including Channing D. Phillips, the acting U.S. attorney; his deputy, Ken Kohl; and the prosecutors leading the effort, including J.P. Cooney, Michelle Zamarin, Gregg Maisel and John Crabb.
In a virtual meeting with all the office’s employees, Mr. Garland complimented their efforts to mitigate the threat in the weeks after the Capitol attack and reiterated the importance of the investigation, according to an attendee.