Attorney general nominee William P. Barr tried Thursday to assuage Senate Democrats’ concerns he might be too biased to oversee the special counsel’s Russia probe, but lawmakers said they would need to hear his answers under oath before they could consider backing his nomination.

“The Mueller probe is the big issue for me . . . he reassured to some extent. The hard questions have to get asked in the public and get on the record,” Sen. Dianne Feinstein (Calif.), the Senate Judiciary Committee’s ranking Democrat, said of her Thursday morning meeting with Barr. She was referring to Robert S. Mueller III, the special counsel investigating Russian interference in the 2016 presidential election and whether anyone in President Trump’s campaign participated in those activities.

Feinstein is one of five Judiciary Committee Democrats who met with Barr on Thursday, after several complained they were being iced out of his schedule and being told it was due to the partial government shutdown. Barr, who served as President George H.W. Bush’s attorney general in the early 1990s, begins his public confirmation hearings before the panel on Tuesday.

“Memo To Whoever Is In Charge: Last time I checked, AG nominee Barr was not a furloughed worker,” Sen. Amy Klobuchar (Minn.), one of the committee’s Democrats who had been told the shutdown might keep her from getting a meeting with Barr, wrote Thursday morning on Twitter .

Klobuchar met with Barr late Thursday, and emerged expressing satisfaction that he told her he would recuse himself from the Justice Department’s appeal of AT&T’s acquisition of Time Warner, as he had been involved in the case. But she expressed continued concerns about his views of Mueller’s probe and “about many of the things he said about executive power.”

Barr has been facing questions from Democrats and Republicans about his previous statements regarding Mueller’s probe, particularly a 2018 memo blasting Mueller for examining whether Trump attempted to obstruct justice in his decision to fire James B. Comey from his post as FBI director. Sen. Sheldon Whitehouse (D-R.I.), another committee member, said that during his meeting with Barr, he asked the nominee to prepare before Tuesday “a complete, thorough and accurate description of what led to his Mueller memo.”

The panel’s chairman, Sen. Lindsey O. Graham (R-S.C.), said Wednesday that Barr would give members a copy of the memo and a list of the people he shared it with and insisted his private opinion would not affect his oversight of Mueller’s probe.

Barr told both Republican and Democratic senators that he will allow Mueller’s investigation “to conclude, to reach its natural investigation unhindered,” committee member Sen. Christopher A. Coons (D-Del.) said after his meeting with Barr.

But such assurances are not necessarily enough to convince Democrats to support him — or have confidence he would stand up to Trump if necessary.

“It is encouraging that the president’s nominated someone who served as attorney general before, but he didn’t serve in a period like this one, where the very rule of law itself is at risk,” Coons said.

Coons said he asked Barr whether he would submit to an official ethics review to determine whether he should recuse himself from overseeing the Mueller probe. Barr told him he might do so “depending on the facts at the time” — and that he didn’t see the memo as reason enough to question his judgment.

Acting attorney general Matthew G. Whitaker last month ignored the advice of Justice Department ethics officials to recuse himself from the Mueller probe. House Democrats want to interview Whitaker about his controversial tenure, and it is clear Senate Democrats are eager to remove him from office as soon as possible.

“He’s like a walking, talking conflict with all of his past activity,” Klobuchar said, but she warned that while she supported proceeding with Barr’s confirmation process, “that shouldn’t be equated with support.”

It is unclear whether Barr will speak with more panel members before his confirmation hearings next week, or whether all other members of the panel have sought an interview with Barr. Sen. Richard Blumenthal (D-Conn.) has requested but not yet received a meeting, but Sen. Cory Booker (D-N.J.) refused twice Thursday to say whether he was seeking time with Barr. Sen. John Neely Kennedy (R-La.) said he did not plan to speak with Barr before his hearing unless the nominee specifically requested it.