Senators are concerned about statements made by William Barr, President Donald Trump's nominee to be the next attorney general.

Republicans have expressed fears that it could devolve into a "character assassination" if they do not like the nominee.

Democrats are not ready to call for Barr's recusal from the special counsel investigation headed by former FBI Director Robert Mueller, but want assurances from him that he will not intervene.

WASHINGTON — Despite the federal government continuing under a partial government shutdown, the Senate Judiciary Committee is moving forward with the confirmation hearing for William Barr to serve as attorney general.

Democrats on the committee have deep concerns about his views on presidential authority and the way he would run the Justice Department, while Republicans are bracing for tense, partisan hearings like they saw during the confirmation process of Supreme Court Justice Brett Kavanaugh.

Read more: Meet William Barr: What you need to know about the possible once and future attorney general

Barr, who served as attorney general under President George H.W. Bush, has drawn outrage and concern from Democrats looking to protect the special counsel investigation into Russian interference during the 2016 presidential campaign. Barr sent an unsolicited memo to the Justice Department calling the special counsel probe "legally unsupportable" and "potentially disastrous."

"As I understand it, his theory is premised on a novel and legally insupportable reading of the law," Barr wrote. "Mueller should not be permitted to demand that the President submit to interrogation about alleged obstruction."

Democrats on the committee told INSIDER that Barr's attitudes toward the special counsel, which is being led by the former FBI Director Robert Mueller, is of the utmost priority.

"I would be very interested in his views on the independence of the Mueller investigation, whether or not he will protect it," Delaware Sen. Chris Coons said. "He has made some statements in the past that give me some concern."

Coons, who is one of the coauthors of a bill that would put barriers in place to prevent the White House from dismantling the special counsel, added that he plans to discuss Mueller's investigation with Barr in private and again in the public confirmation hearing.

Whether Barr should recuse himself from oversight of the Mueller probe, Coons said he was not yet sure that would be necessary, but would have to receive commitments before making a decision.

"I mean I think were he to announce that he intended to leave it in its current structure where it is being supervised very ably by Rod Rosenstein, that would be met with fairly broad enthusiasm," Coons said.

Colleagues of Coons, including Sens. Amy Klobuchar and Richard Blumenthal, also listed Barr's position on the special counsel as a top priority, as well his views on executive power as a whole.

"High on the list [of concerns] is an absolute ironclad assurance and commitment that there will be no interference in the special counsel investigation, including prompt and complete approval of subpoenas, other investigative tools, and any indictments that are returned by the grand jury," Blumenthal told INSIDER.

Republicans want the confirmation hearing to remain civil

Senate Republicans are clearly scarred from what became one of the most tense processes in years during the Kavanaugh confirmation.

"I guess the question we all have is this going to be Kavanaugh 2.0 where it’s really not about searching for the truth — it’s more about character assassination," Sen. John Cornyn of Texas told reporters on Tuesday. "I’m an optimist by nature, so I can hope for the best but we’ll have to wait and see."

Sen. Lindsey Graham of South Carolina said he is doing what he can "to make sure that our Democratic friends have information relevant to voting for or against Mr. Barr," but cautioned against things getting out of hand.

Graham, who himself launched a fierce tirade during the Kavanaugh hearing to excoriate Democrats he saw as politicizing the process, now will have to walk a more fine line. In the 116th Congress, he is taking over the gavel as the new chairman of the Judiciary Committee and maintain order in tense hearings.

"I expect him to be challenged and appropriately challenge him about his memo and other things," Graham said. "I just hope it’s done respectfully. I’m trying to set a tone where we can have our differences and move forward."