The fate of a final report on special counsel Robert Mueller III's investigation took center stage at a Senate hearing Wednesday, as witnesses testifying on William Barr's nomination as U.S. attorney general debated his commitment to sharing Mueller's findings with the public.

The witness panel, featuring law professors, a former attorney general, and the leaders of civil rights groups, capped the nominee's two-day confirmation hearing, which was mostly dominated by the topic of Mueller's probe into Russian interference in the 2016 election.

Barr on Tuesday sought to assuage Democrats' concerns that he might undermine the probe, vowing to allow the special counsel to complete his work. But he signaled he might not release a full report on Mueller's findings to lawmakers and the public, only promising senators he would “provide as much transparency” as he could, consistent with Department of Justice regulations.

Barr later told Sen. Richard Blumenthal, D-Connecticut: “Under the current regulations, the special counsel report is confidential, and the report that goes public would be a report by the attorney general.”

Sen. Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, said Wednesday she was concerned by Barr's “equivocation” on the matter of a final report. Feinstein said Barr's answer suggested he, at the conclusion of Mueller's probe, might only release a report prepared by the attorney general—rather than Mueller's findings—to lawmakers.

“I think it is essential that the American people know what is in the Mueller report,” Feinstein said, noting that she would follow up with the nominee in writing. She added: “I am hopeful that that report will be made public, and my vote depends on that.”

Echoing that concern on Wednesday was Neil Kinkopf, a law professor at Georgia State University's law school. Kinkopf said Barr made clear that he interpreted DOJ regulations to mean that he did not need to release Mueller's findings—only that he would release his own report.

Kinkopf predicted that “Barr will take the position that any discussion or release of the Mueller report—relating to the president, who again cannot be indicted—would be improper and prohibited by DOJ policy and regulations.”

Jonathan Turley, a professor at George Washington University's law school defended Barr's refusal to commit to full disclosure. He said Barr could not “commit in advance” to the release of information that he had not yet seen, because “part of his duty is to protect” things such as grand jury-related or privileged information. “He's duty-bound to review that,” Turley said in an exchange with committee Chairman Lindsey Graham, R-South Carolina.

“The only thing a nominee can say is that he is going to err on the side of transparency, and try to get as much of the report to Congress as possible,” Turley said.

Wednesday's discussion also turned toward an unsolicited memo Barr sent to the Justice Department and other lawyers last June. The memo has fallen under scrutiny in part for Barr's comments criticizing a possible obstruction of justice inquiry as “fatally misconceived.”

Barr had defended those comments during Tuesday's hearing, describing the memo as “narrow in scope” and focused on a single obstruction theory he believed Mueller might have been pursuing, rather than an attack on the special counsel investigation itself.

Still, Kinkopf argued the memo illustrated Barr's “alarming” views on executive power. Under the theory Barr espouses in his memo, Kinkopf warned, Trump would have the power to fire Mueller, terminate and tinker around with his probe, and more.

Defending Barr's integrity and independence Wednesday were two former top Justice Department officials: Larry Thompson, a former deputy attorney general during the George W. Bush administration and now counsel at Finch McCranie, called Barr's integrity “rock solid.”

Michael B. Mukasey, former U.S. attorney general, and former U.S. district judge for the Southern District of New York, and now of counsel with Debevoise & Plimpton, testifies before the Senate Judiciary Committee during confirmation hearing for U.S. Attorney General candidate William Barr, on Wednesday, Jan. 16, 2019. Photo: Diego M. Radzinschi/ALM

Barr's “history of government service is simply without equal in suiting him to serve as attorney general,” said Michael Mukasey, former attorney general under Bush and now of counsel at Debevoise & Plimpton.

Also appearing at Wednesday's hearing were the heads of two of civil rights organizations: Derrick Johnson of the NAACP and Marc Morial of the National Urban League, who urged senators to reject Barr's bid, arguing civil rights enforcement could suffer under a Barr Justice Department.

Wednesday's panel also included former presidential speechwriter Mary Kate Cary, the Rev. Sharon Washington Risher, and Chuck Canterbury from the Fraternal Order of Police.