WASHINGTON — President Trump on Friday said he intended to nominate William P. Barr, who served as attorney general during the first Bush administration from 1991 to 1993, to return as head of the Justice Department.
“He was my first choice since Day 1,” Mr. Trump told reporters as he walked from the White House to a helicopter for a trip to Kansas City, Mo. “He’ll be nominated.”
Mr. Trump’s focus on Mr. Barr, who supports a strong vision of executive powers, had emerged over the past week following the ouster last month of Jeff Sessions as attorney general and the turbulent reception that greeted his installation of Matthew G. Whitaker as the acting attorney general.
The move at the Justice Department is one part of a larger staff shake-up underway.
Mr. Trump also announced that Heather Nauert, the chief State Department spokeswoman, is his pick to be the next ambassador to the United Nations.
In addition, John F. Kelly, the White House chief of staff, is likely to leave his post in the next few days, ending a tumultuous 16-month tenure still among the longest for a senior aide to Mr. Trump, two people with direct knowledge of the developments said Friday.
Mr. Kelly and Mr. Trump have grown weary of each other. But Mr. Trump, according to several senior administration officials and people close to him, has so far been unable to bring himself to personally fire a retired four-star military general.
It is unclear who the replacement for Mr. Kelly would be. Nick Ayers, the vice president’s chief of staff, is seen as a leading candidate. He is supported by Jared Kushner and Ivanka Trump, the president’s son-in-law and daughter, who both serve as senior West Wing advisers and who, according to several officials, are trying to expand their influence internally and in the re-election campaign.
The White House senior staff meeting on Friday morning was canceled, according to three officials. But there is a holiday senior staff dinner scheduled for Friday night, and people said they expected Mr. Kelly to be there.
While Mr. Trump could replace Mr. Kelly with a new chief of staff at his own discretion, Mr. Barr will have to be confirmed by the Senate.
On Thursday, as expectations swelled that Mr. Barr had emerged as the front-runner for the nomination, Senator John Cornyn of Texas, the No. 2 Senate Republican, called Mr. Barr a “very good choice” and predicted that Republicans would be able to secure the votes needed to confirm him — one of the highest potential hurdles for any Justice Department nominee given the ongoing special counsel investigation.
“He is the kind of person who could get confirmed,” he said. “I think it is going to be challenging in any event.”
Mr. Barr has criticized aspects of the Russia investigation, including suggesting that the special counsel, Robert S. Mueller III, hired too many prosecutors who had donated to Democratic campaigns. Mr. Barr has defended Mr. Trump’s calls for a new criminal investigation into his 2016 opponent, Hillary Clinton, including over a uranium mining deal the Obama administration approved when she was secretary of state.
“There is nothing inherently wrong about a president calling for an investigation,” Mr. Barr told The New York Times last year. “Although an investigation shouldn’t be launched just because a president wants it, the ultimate question is whether the matter warrants investigation.”
Mr. Barr added then that he saw more basis for investigating the uranium deal than any supposed conspiracy between Mr. Trump’s associates and Russia. “To the extent it is not pursuing these matters, the department is abdicating its responsibility,” he said.
Mr. Barr has assembled a “generally mainstream G.O.P. and corporate” reputation, Norman L. Eisen, who served as special counsel for ethics and government overhaul under President Barack Obama, said on Thursday. But he predicted that Mr. Barr would be vigorously vetted because of what he saw as blots on Mr. Barr’s record, including his push for scrutiny of the mining deal, involving a company called Uranium One.
Mr. Barr “has put forward the discredited idea that Hillary Clinton’s role in the Uranium One deal is more worthy of investigation than collusion between Trump and Russia,” Mr. Eisen wrote in a text message. “That is bizarre. And he was involved in the dubious George H.W. Bush end of term pardons that may be a precedent for even more illegitimate ones by Trump.”
Senator Richard Blumenthal, Democrat of Connecticut, said on Friday that Democrats will vet him closely.
“I will demand that Mr. Barr make a firm and specific commitment to protect the Mueller investigation, operate independently of the White House, and uphold the rule of law,” he said in a statement. “The Senate must closely scrutinize this nominee, particularly in light of past comments suggesting Mr. Barr was more interested in currying favor with President Trump than objectively and thoughtfully analyzing law and facts.”
A graduate of George Washington University’s law school, Mr. Barr, 68, got his start in the 1970s working for the C.I.A. and later worked in the Reagan White House before leaving for private practice. In 1989, President George Bush appointed him to lead the Justice Department’s powerful Office of Legal Counsel, and later elevated him to deputy attorney general and then attorney general.
After the Bush administration, Mr. Barr spent most of his postgovernment career as the top lawyer for the telecommunications company that became Verizon, from which he retired in 2008. He later joined the Kirkland & Ellis law firm.
In a November 1992 speech, Mr. Barr put forward the ideal of an attorney general whose primary loyalty is to the rule of law, not to the president who appointed him — saying that he must provide “unvarnished, straight-from-the-shoulder legal advice” with no regard to political considerations like what conclusions the White House might prefer.
“The unique position of the attorney general raises special considerations,” Mr. Barr said. “The attorney general’s oath to uphold the Constitution raises the question whether his duty lies ultimately with the president who appointed him or more abstractly with the rule of law. I said in my confirmation hearings, and have said several times since, that the attorney general’s ultimate allegiance must be to the rule of law.”
Still, he also said that in his experience, he confronted no conflicts between his duty to uphold the law and his policy allegiance to the president.
Perhaps not coincidentally, Mr. Barr developed a reputation as a proponent of a sweeping theory of the president’s constitutional authority to act without congressional permission or in defiance of statutes.
In July 1989, shortly after his appointment to the Office of Legal Counsel, Mr. Barr sent an apparently unsolicited 10-page memo to top agency and department lawyers across the executive branch urging vigilance in pushing back against ways in which Congress might try to intrude on what he saw as the rightful powers of the president. It covered topics such as “attempts to gain access to sensitive executive branch information” and efforts to limit a president’s power to fire a subordinate official without a good cause.
“It is important that all of us be familiar with each of these forms of encroachment on the executive’s constitutional authority,” Mr. Barr wrote. “Only by consistently and forcefully resisting such congressional incursions can executive branch prerogatives be preserved.”
Years later, in 2005, after the leaking of a secret George W. Bush administration memo blessing the torture of terrorism detainees despite anti-torture laws and treaties, Neil Kinkopf, a Georgia State law professor who worked in the Office of Legal Counsel during the Clinton administration, pointed back to Mr. Barr’s 1989 memo as a precursor to the torture memo’s vision of unfettered executive power.
“Never before had the Office of Legal Counsel, known as the O.L.C., publicly articulated a policy of resisting Congress,” Mr. Kinkopf wrote in a Legal Affairs essay. “The Barr memo did so with belligerence, staking out an expansive view of presidential power while asserting positions that contradicted recent Supreme Court precedent.”
He added, “Bridging a 15-year gap, the Barr memo provides the theoretical and strategic foundations for the torture memo.”
Many proponents of strong presidential powers nevertheless say that Congress can check the presidency through its power over government spending. But at a 1990 symposium, Mr. Barr invoked a constrained understanding of lawmakers’ ability to cut off funds for government actions they oppose, declaring that “Congress cannot use the appropriations power to control a presidential power that is beyond its direct control.”
And when issues of war power came up — like Mr. Bush’s 1989 invasion of Panama, the 1990-91 Persian Gulf War or the 1992 deployment of troops to Somalia — Mr. Barr repeatedly told Mr. Bush that he could deploy American troops without specific prior authorization from Congress.
One drawback from Mr. Trump’s perspective may be that in 1992, Mr. Barr decided to trigger the appointment of an independent counsel to investigate whether senior Bush administration officials had committed a crime by searching Bill Clinton’s passport file while he was a presidential candidate. The prosecutor took three years to finish that investigation, ultimately concluding that no crime had been committed and that he should not have been appointed.
But at a 1997 panel discussion on the independent counsel law, Mr. Barr criticized the statute and expressed concern about using the criminal justice system to prosecute high-level executive branch officials over minor offenses, saying such conduct should be checked by politics. The context was allegations that the vice president at the time, Al Gore, had made political fund-raising calls from inside the White House.
“I’m not going to prosecute the vice president of the United States because he made five phone calls to raise money from the White House — it’s ridiculous. It’s not in the public interest,” Mr. Barr said, adding: “Let the attorney general take the heat, if there is heat, publicly for it.”