President Donald Trump's attorney general nominee, William Barr, appeared to dismiss one of the president's most consistent attacks on special counsel Robert Mueller: that his probe of Russian election interference is a "witch hunt."

Barr, who on Tuesday faced questions from the Senate Judiciary Committee during his confirmation hearing, was asked by Chairman Lindsey Graham, R-S.C., about Trump's characterization of the probe of Russian meddling and possible collusion with the Trump campaign.

"Do you believe Mr. Mueller would be involved in a witch hunt against anybody?" Graham asked Barr.

Barr, who had already served as attorney general once before in the administration of President George H.W. Bush, responded directly: "I don't believe Mr. Mueller would be involved in a witch hunt."

The White House did not immediately respond to CNBC's request for comment on Barr's remarks. A spokesman for the special counsel's office declined to comment.

Trump has repeatedly the special counsel's probe a "witch hunt" since Mueller's appointment in May 2017, and on occasion has called it "phony" and "illegal." In November, Trump called Mueller "a conflicted prosecutor gone rogue."

Barr's Senate testimony, in contrast, referred to Mueller as fair-minded, even to the president, and said, "We were good friends" during their time working in government together.

The 68-year-old Barr was questioned about the special counsel by committee members of both parties from the start of his first confirmation hearing, and himself addressed the Russia probe in his prepared remarks. He promised that, if confirmed, "Bob will be allowed to complete his work."