"I'm going to do what I think is right", Barr said at his confirmation hearing before the Senate Judiciary Committee.
Barr, who met with lawmakers last week to ensure them he would uphold the investigation, will tell the senators that the president "sought no assurances, promises, or commitments from me of any kind, either express or implied".
Democrats - and perhaps Republicans - are sure to have questions about Barr's approach to Mueller, especially since Barr has been critical of the Mueller probe in the past. If Barr is confirmed by then, he'll have the final say, unless a conflict of interest required him to recuse himself from being in charge of Mueller. Rosenstein will reportedly step down as Deputy AG after Barr's confirmation, which seems highly probable given Republican control of the Senate.
Trump has repeatedly castigated Mueller's investigation, calling it a "witch hunt", and lambasted and ultimately pushed out his first attorney general, Jeff Sessions, for removing himself from the matter because of his work with the 2016 Trump campaign.
"It's unimaginable to me that Bob would ever do anything that gave rise to good cause", Barr said.
Mueller has reportedly been investigating possible collusion between the Trump campaign and Russian government as well as possible obstruction by Trump over the firing of James Comey as Federal Bureau of Investigation director.
Chris Pratt, Katherine Schwarzenegger engaged
Pratt took to Instagram to confirm the news post a picture of the two sharing a heartfelt along with an emotional message. The Jurassic World star has proposed to action star Arnold Schwarzenegger's daughter after just seven months of dating.
"It does raise questions about your willingness to reach conclusions before knowing the facts, and whether you prejudge the Mueller investigation", said Senator Dianne Feinstein, the Judiciary Committee's top Democrat.
Barr told Democratic Senator Amy Klobuchar last week that he would recuse himself from the Justice Department's efforts to block the merger of AT&T and Time Warner Inc.
"I believe it is vitally important that the special counsel be allowed to complete his investigation", Barr said in prepared remarks. Barr even referred to Mueller in friendly fashion, having worked with him back in the 1990s when Barr was attorney general.
The special counsel is required to confidentially report his findings to the Justice Department.
Barr pledged that, if confirmed, he would not allow "partisan politics, personal interests, or any other improper consideration" to interfere with Mueller. He told The Hill past year that "leaks" from the special counsel's office "raise questions as to whether there is an agenda" and suggested that Mueller's team was not politically "balanced," as some members had made political contributions to Democratic candidates. Writing as a "former official deeply concerned with the institutions of the Presidency and Department of Justice", Barr argued, "Mueller should not be permitted to demand that the President submit to interrogation about alleged obstruction". He said presidents can not be criminally investigated for actions they are permitted to take under the Constitution, such as firing officials who work for them, just because of a subjective determination that they may have had a corrupt state of mind.
"The memo did not address - or in any way question - the special counsel's core investigation into Russian interference in the 2016 election", Barr said.
Barr also said it was "very important" that Congress and the public be informed of what Mueller investigated and concluded. In the past, Barr has supported Trump's firing of FBI Director James Comey, which led to Mueller's appointment and an investigation of possible obstruction of justice.