Mr. Barr shed some additional light on Mr. Mueller’s decision not to reach a prosecutorial decision about whether Mr. Trump criminally obstructed the investigation and his own decision to conclude in his letter to Congress delivering the investigation’s conclusions last month that the evidence did not meet that bar.

Mr. Barr said he had spoken with Mr. Mueller about why he did not reach a decision on obstruction of justice, but declined to offer details of their conversations. The attorney general said that Mr. Mueller did not explicitly ask that Congress be allowed to judge the evidence and decide for itself, nor did he say that the attorney general should.

“But that is generally how the Department of Justice works,” Mr. Barr said, saying that the department’s job is to make prosecutorial decisions — and he had.

“I am looking forward to explaining my decision that I briefly outlined in the March 24 letter, but I don’t think I can do it until the report is out,” he said.

The redacted Mueller report may be released “next week,” Barr says.

On the timing of the redacted report’s release, Mr. Barr said Wednesday that he “hoped” to make it public “next week.” The answer differed slightly from what he told House lawmakers on Tuesday, that he intended to put out the report “within a week.”

He said Justice Department lawyers and members of Mr. Mueller’s team, who are reviewing the report for sensitive information to black out before release, would not remove information that would harm the “reputational interests” of Mr. Trump. Mr. Barr also said that he had not overruled Mr. Mueller’s team on any proposed redactions from the Mueller report, and had not discussed with the White House what he was blacking out.

Barr is willing to work with Congress on redacted information.

Democrats in the House have slammed Mr. Barr for what they view as his refusal to share the investigation’s underlying evidence and material he may redact from the report. But Mr. Barr told senators on Wednesday he would be willing to re-evaluate that decision to try to accommodate lawmakers’ concerns.