Barr is expected to win confirmation in the Republican-controlled chamber as soon as next week, after the Senate Judiciary Committee voted to approve him by a party-line vote of 12 to 10.
In a statement Thursday afternoon, Sen.
"We need a new attorney general", Graham said on Thursday.
You can read Sen.
Multiple legal and constitutional scholars have argued that Whitaker's appointment to acting attorney general was unconstitutional because he was not confirmed to the position by the US Senate.
If confirmed by the full Senate, Barr will assume oversight of Mueller's investigation, which has focused on possible collusion between the Trump campaign and Moscow during the 2016 USA presidential election and whether the president obstructed justice, among other things.
Barr promised he would "not allow" Trump's legal counsel's Rudy Giuliani's expressed desire to "edit" the Mueller report before being released.
Graham said that if Barr were to prevent release of a report by Mueller, he would support legislation being pushed by Senators Chuck Grassley, Republican of Iowa, to require full transparency from the Special Counsel.
The nominee was attorney-general once before, under president George HW Bush.
Republicans said they were confident Barr would make as much of the report public as possible.
I said 'You got a lot of good choices here.' And he asked about Bill Barr I said, 'That would be a great choice I think because you know what you are getting.
But Durbin said Barr has "telegraphed his pitch" by writing an unsolicited memo to Justice Department and Trump lawyers previous year about parts of the special counsel probe.
Democrats on the U.S. House of Representatives' Judiciary Committee on Thursday prepared a subpoena to compel Whitaker to testify on Friday, prompting him to say he will not appear unless the subpoena threat is lifted.
If he wins the job, Barr's independence could be put to the test when Mueller wraps up his investigation into the Trump campaign's possible ties to Russian Federation during the 2016 election.
Whitaker said late last month the Mueller-led investigation is "close to being completed", although there has been no confirmation of this from the special counsel's office.