Senators debated Barr's candidacy for several hours, focusing on his potential role in supervising special counsel Robert Mueller in the Russian Federation investigation.
Support for a public release stands at 80 percent among Republicans who say they approve of the way President Trump is handling his job and 92 percent among Democrats who say they don't approve of how the president is doing his job.
"We need a new attorney general", Graham said on Thursday.
Sen. Amy Klobuchar (D-Minn.) said that Barr, as attorney general, would have the authority to change policies that now might prohibit him from revealing information about Mueller's work and that his nomination must be considered in the context of the historic moment in which the Justice Department finds itself. Patrick J. Leahy (D-Vt.) said he was concerned Barr's previous testimony on the subject "could lay the groundwork for potentially no transparency at all". Barr has said he will be as transparent as possible under Justice Department regulations, but many Democrats are skeptical.
Barr promised he would "not allow" Trump's legal counsel's Rudy Giuliani's expressed desire to "edit" the Mueller report before being released.
Trump then made the highly controversial decision to install Sessions' chief of staff, Matthew Whitaker, as acting attorney general.
"I appreciate what Mr. Whitaker has done, but I think it's time for new leadership at the department", Sen. Chuck Grassley, an Iowa Republican, and Richard Blumenthal, Connecticut Democrat, introduced legislation requiring a special counsel to submit a report to Congress.
"I don't believe Mr. Mueller would be involved in a witch hunt", Barr said.
Barr was selected after former attorney general Jeff Sessions was pushed out in November 2018.
All 12 Republicans on the panel voted for Barr, while all 10 Democrats voted against him.
Barr, the architect behind many tough-on-crime policies that led to disproportionately high rates of incarceration in the African-American community, acknowledged the disparate impacts of those laws and committed to fully enforcing the First Step Act, a piece of landmark criminal justice reform legislation signed into law by Trump in December.
"I hope I'm wrong", Durbin said.
Catholic William Barr is expected to be approved by the full Senate next week. Barr, meanwhile, scheduled several individual meetings with lawmakers, seeking to answer whatever outstanding questions they might have had. "I don't know what Bob Mueller is writing", Barr said at his hearing last month.