It's the first time senators have questioned Barr since last month's release of the redacted Mueller report -- which concluded there was no evidence President Donald Trump's 2016 campaign colluded with Russia. It also listed several "episodes" in which it said Trump potentially obstructed justice -- including his firing of FBI Director James Comey and discussions of firing Mueller.
Barr told the Senate judiciary committee Wednesday he wasn't sure anything outlined in the report amounts to obstruction of justice.
"The president can direct the termination or the replacement of a special counsel and as a matter of law the obstruction statute doesn't reach that conduct," Barr said. "Even if it reached the conduct, could you here establish corrupt intent beyond a reasonable doubt?
"The evidence now suggests that the accusations against [Trump] were false and he knew they were false. And he felt this investigation was unfair, propelled by his political opponents and was hampering his ability to govern. That is not a corrupt motive for replacing an independent counsel."
Barr's Senate testimony came on the same day he told the House judiciary committee he will not testify before the panel Thursday as expected.
Ranking member Doug Collins said it was "a shame" the panel wouldn't get to interview Barr because House Democrats sought to have a counsel question him.
"By rejecting the chance to question Attorney General Barr or read the materials he's provided, Democrats are trying to prolong an investigation the special counsel completed," Collins, R-Ga., said.
Democrats were highly critical of Barr in March when he gave only a four-page summary of the Mueller report. Weeks of wrangling eventually produced the redacted version, but the department has still yet to release the full version to lawmakers or the public. Mueller sent Barr a letter in late March, which was revealed Tuesday, saying he didn't think the summary accurately represented the crux of the investigation.
"The summary letter the department sent to Congress and released to the public late in the afternoon of March 24 did not fully capture the context, nature and substance of this office's work and conclusions," Mueller wrote in the letter. "There is now public confusion about critical aspects of the results of our investigation. This threatens to undermine a central purpose for which the department appointed the Special Counsel: to assure full public confidence in the outcome of the investigations."
Mueller urged Barr to release the report in late March, saying it would provide transparency for the public.
"Release at this time would alleviate the misunderstandings that have arisen and would answer congressional and public questions about the nature and outcome of the investigation," Mueller wrote.
At the time, Barr was pressured by Democrats to release the report but the attorney general said he needed more time to redact sensitive information.
When asked about the letter Wednesday, Barr told lawmakers Mueller had never indicated he had any problem with the summary.
Barr also made clear in his opening remarks his work on the Mueller report is finished, and said the near 400-page Mueller report is now his "baby."
"The responsibility of the Department of Justice, when it comes to law enforcement, is to determine whether crimes have been committed and to prosecute those crimes under the principles of federal prosecution," Barr said. "With the completion of the special counsel's investigation and the resulting prosecutorial decisions, the department's work on this matter is at an end."
Barr said, though, the department will continue prosecutions already underway and make a separate inquiry into the FBI's conduct during the Russia investigation, as to its use of the Foreign Intelligence Surveillance Act.