The attorney general’s deliberative approach has come to frustrate Democratic allies of the White House and, at times, President Biden himself. As recently as late last year, Mr. Biden confided to his inner circle that he believed former President Donald J. Trump was a threat to democracy and should be prosecuted, according to two people familiar with his comments. And while the president has never communicated his frustrations directly to Mr. Garland, he has said privately that he wanted Mr. Garland to act less like a ponderous judge and more like a prosecutor who is willing to take decisive action over the events of Jan. 6…

Mr. Biden, a longtime creature of the Senate, is aghast that people close to Mr. Trump have defied congressional subpoenas and has told people close to him that he does not understand how they think they can do so, according to two people familiar with his thinking.

Mr. Garland has not changed his approach to criminal prosecutions in order to placate his critics, according to several Justice Department officials who have discussed the matter with him. He is regularly briefed on the Jan. 6 investigation, but he has remained reticent in public.