Democrats scolded Barr over his handling of the report, telling him they were concerned that a summary of its main conclusions he released last month portrayed the investigation's findings in an overly favourable way for President Donald Trump. "First is grand jury information..."
He added that he is relying on his own discretion to make as much public as he can.
Facing the intensifying concerns from Democrats that he may have whitewashed Mueller's findings, Barr has twice moved to defend, or at least explain, his handling of the process since receiving the special counsel's report. "Democratic congressmen on the committee... they're saying we'll be coming at you hard".
"I will consider whatever it takes to get people to see this report", said Representative José Serrano, D, chairman of the Appropriations commerce, justice, science and related agencies subcommittee. "This report is too important to all of us".
Mueller turned over his confidential report to Barr on March 22 following a 22-month-long probe into whether Donald Trump may have colluded with Russian Federation during his 2016 presidential campaign and whether Trump later obstructed inquiries into the matter.
Asked about the House Democrats mulling a subpoena to force Barr to release the unredacted report, the attorney general said, "there's been a recent case decided in the District of Columbia just, I think within the last week, on this that 6 (e) material is not releasable". Mueller, however, had not made any recommendation on such a charge. "The letter on the 29th, I don't believe that was reviewed by Mr. Mueller or that they participated in drafting that letter".
"From a prosecutor's standpoint", he said, "the bottom line is binary, which is charges or no charges".
And in his testimony on Tuesday, Barr expressed skepticism that giving Congress - let alone the public - grand jury information, as covered in the law referred to as "6 (e)", could ever be appropriate. And he does not plan on seeking a court order to release grand jury information (which, according to the Federal rules of criminal procedure, must be kept secret unless certain exceptions are met), something Democrats have demanded in recent days.
Barr is testifying at a House appropriations subcommittee hearing to discuss the Justice Department budget and the department's priorities, but the Mueller report - which Barr is in the process of redacting before releasing publicly - will loom over the proceedings. He said that he will colour-code the redactions and provide "explanatory notes" so people know why various sections of the report are not being disclosed.
"If you seek both transparency and for the American public to learn the full contours of the Special Counsel's investigation, public testimony from Special Counsel Mueller himself is undoubtedly the best way to accomplish this goal", Collins wrote in his letter Monday.
Cartwright countered that Barr is devoting the Justice Department's "scarce resources" to the case. He said of Barr: "He has been unresponsive to our requests". He added, "My intention is not to ask for it at this stage".
Barr reiterated the four categories of information he wants to redact from the Mueller report before its release.
If Trump did get more than the synopsis, it could have helped the White House with its efforts to spin the entire investigation as a time-wasting "witch hunt" that had nonetheless "exonerated" him, whether or not the report actually supported that interpretation. The Trump administration, which initially said Obamacare's insurance protections should be struck down as unconstitutional, is now seeking to overturn the ACA in its entirety.