The president said in a statement that Whitaker would fill the role of acting US Attorney General until a permanent replacement is found. With the current session of Congress set to soon end, anyone Trump nominates may have to wait until well into 2019 for confirmation.
Mr Barr retired from his position as counsel and executive vice-president of Verizon in 2008. "Those are the best attorneys general", said Democratic Sen.
The Mueller probe has been an Achilles heel for the office of attorney general the past couple of years. Patrick Leahy, D-Vt., before Barr's hearing on November 12, 1991.
Mr Barr has voiced disapproval over some aspects of the inquiry but his views on the investigation's legitimacy remain unknown.
Barr also said James Comey's firing was "understandable" and that he "crossed a basic line" and "transgressed" in his role as Federal Bureau of Investigation director.
"He was my first choice since day one", Trump said. In remarks to the New York Times, Barr addressed the notion of the Justice Department investigating Trump's 2016 opponent, Hillary Clinton.
The presidents' aides had previously floated the idea of Barr retaking his post in the Justice Department, sources said, with an announcement expected next week.
Rove noted Barr respects Mueller, who led the FBI's criminal division when the former was AG under Bush.
Barr's comments on Mueller and Clinton could stir opposition from Senate Democrats, but the nomination will nearly certainly not come up for a vote until next year. In 2017, he told The Washington Post that "prosecutors who make political contributions are identifying fairly strongly with a political party".
One of the people who spoke to the AP said there have been discussions among senior administration officials about Barr's willingness to do the job, and said the belief was that he was open to doing it if asked. I was happy that GTE's conduct of the litigation was considerably more aggressive than that of other similarly situated carriers who were also required to share their facilities and equipment with new competitors under the Act. Joe Biden, who said Barr should be "complimented" for his "candid answer", even though the eventual US vice president did not agree.
At least one other contender who has received serious consideration from the White House, according to the person, is Rep. John Ratcliffe, a Texas Republican.