WASHINGTON - President Trump on Friday accelerated a long-anticipated shake-up of his Cabinet in the wake of the midterm elections, naming new picks for attorney general and U.N. ambassador amid widespread speculation that the embattled White House chief of staff John Kelly could soon depart.

Trump confirmed his choices of William Barr to lead the Justice Department and Heather Nauert for the United Nations post as he left the White House, speaking to reporters over the din of whirring blades from Marine One.

If confirmed by the Senate, Barr will take over for acting attorney general Matthew Whitaker. An unfettered Trump installed him in place of the ousted Jeff Sessions less than 24 hours after the polls closed on Nov. 6 in the first move of an expected overhaul of Cabinet secretaries and senior White House aides.

After a CNN report Friday morning that Kelly could be stepping down in a matter of days, Trump did not pause long enough to take questions from reporters, though he teased he would make another big personnel announcement Saturday at the Army-Navy game in Philadelphia.

"I can give you a little hint: It will have to do with the Joint Chiefs of Staff and succession," Trump said.

Several U.S. officials said Trump will tap Gen. Mark Milley as his next top military adviser, choosing a battle-hardened commander who has served as chief of the Army for the last three years.

If confirmed by the Senate, Milley would succeed Marine Gen. Joseph Dunford as chairman of the Joint Chiefs of Staff, the pinnacle of a military career. Dunford, a former commandant of the Marine Corps and commander of coalition troops in Afghanistan, is expected to serve out his term as Joint Chiefs chairman, which ends next Oct. 1.

Milley, who commanded troops during several tours in Iraq and Afghanistan, has served as the Army’s top officer since August 2015.

Kelly was not at work Friday morning, though an ally said he was simply taking a day off and would be at the White House for a holiday staff dinner Friday night. The lights were off in his West Wing office.

He has not been asked to resign, this person said, requesting anonymity to speak candidly about a personnel matter.

Among White House officials, however, there is broad consensus that his days as chief of staff are numbered.

One senior administration official said Friday that it's clear Kelly will be leaving though said it's not certain that the departure was imminent as CNN reported. The official requested anonymity to discuss a sensitive matter.

Trump has engaged in talks with Nick Ayers, the vice president's chief of staff, about taking over the position, advisers said. The president often remarks on Kelly's lack of political skills and has told advisers in recent days that he needs a more political chief of staff for his reelection. Ayers, a sharp-elbowed and ambitious Georgia operative, fits the bill, advisers said.

But the story line of Kelly's departure has been protracted for so many months that White House aides often now just shrug.

"Sure, Trump says he wants him gone, and Kelly swears and leaves and says he's not coming back. But then he comes back," said one former senior administration official, who requested anonymity to offer a candid assessment.

Kelly, a retired four-star Marine Corps general, has been the president's top aide since late July 2017. Trump has chafed at Kelly's management style and resisted some of his moves to instill discipline in the West Wing and contain chaos. In recent months, the chief of staff's power has ebbed, with administration policies and decisions being guided more by the president's gut instincts than by Kelly's processes.

Washington has been abuzz with rumors about Kelly's job status have been rampant at various moments during his 16-month tenure. But this past summer, Kelly sought to quiet speculation that he was nearing the exist because of tensions with Trump by telling senior staff that he intended to remain as chief of staff through Trump's 2020 reelection campaign.

Trump and Kelly have privately argued at times and complained about one another to confidants, sometimes in colorful language. But the two men are generational peers have a measure of respect for one another, and they have bonded over their shared ideology, especially on immigration issues, and their mutual grievances toward the media and political establishment.

Trump has long admired Kelly for his military valor, but his lack of political experience and interest in campaign strategy has made him an imperfect fit leading the staff of a president who lives and breathes politics. As Trump prepares for his 2020 reelection campaign, some advisers have counseled him to replace Kelly with a sharper operative who can steer the administration through the daily - and hourly - political fights sure to come.

Trump had nothing but praise for the two new Cabinet members who he announced Friday that he would nominate for the Senate.

He told reporters that Barr, who led the Justice Department under former president George H.W. Bush, was "my first choice since day one" and said is "a terrific man, a terrific person, a brilliant man."

Nauert, 48, joined the State Department last year with no government experience after a career as an anchor and correspondent at Fox News.

“She’s very talented, very smart, very quick, and I think she’s going to be respected by all,” Trump said.