Donald Trump plans to head to Mar-a-Lago for a 16-day Christmas vacation starting Friday—and West Wing officials, remembering previous sojourns, are on edge at the prospect of the president spending two weeks unsupervised. As the Robert Mueller loop tightens around the president, his erratic behavior is causing alarm among his most senior staff. “The staff is fed up he’s acting like a nut. They can’t get him to stop tweeting,” a former official said.

Trump still has the ability to compartmentalize, and his mood has yo-yoed. Last night, he was jovial at a White House Christmas party attended by Don Jr. and Kimberly Guilfoyle, Ryan Zinke, Scott Walker, Chris Christie and Diamond and Silk. “He truly lives in separate worlds,” another former official observed. Trump’s advisers, however, recognize the precariousness of the current political moment. In one sign of the discontent in the West Wing, Communications Director Bill Shine has told friends that he’s thinking about signing a month-to-month lease for his Washington apartment, according to a source. “Bill is very frustrated,” a person familiar with his thinking said.

Trump’s freewheeling search to replace John Kelly as chief of staff unnerved Ivanka and Jared Kushner, three sources briefed on the discussions said. Trump, who was annoyed at Kushner after Kushner’s pick, Nick Ayers, turned down the job, told people he was seriously considering Citizens United president David Bossie. Kushner told people that giving Bossie the job would empower Bossie’s friend and co-author Corey Lewandowski, a longtime Kushner nemesis. (Last week, Bossie and Lewandowski met with Trump at the White House, a source said.) Bossie is also an ally of Steve Bannon, another Kushner enemy. “Jared got Steve Mnuchin and his buddies to tell Trump no way,” a source briefed on the discussions said. With few candidates available or willing to take the job, Kushner pushed Trump to name budget director Mick Mulvaney chief of staff. “They announced it as ‘acting’ but he’s chief. They only did that so if he and Trump hate each other they have an off-ramp,” the source said.

West Wing officials anticipate more departures—and worry that filling the jobs may be difficult. “I want them all out,” Trump fumed to officials, referring to Kelly’s loyalists, a person briefed on the conversation said. Sources said Deputy Chief of Staff Zach Fuentes and counselor to the president John DeStefano are likely to leave. “You got tumbleweeds blowing through the West Wing. It’s already understaffed,” a former official told me. Kelly also remains a source of suspicion. According to a source, allies of Trump have told the president that Kelly could leak to reporters once he’s out of the White House, and are pushing Trump to get Kelly to sign an additional non-disclosure agreement. “People are worried that Kelly will be out there dropping bombs,” the source said.

And then, of course, there’s Mueller. “They have no idea what [the] report will say,” a Republican close to the White House said. That is why Rudy Giuliani has been floating the newest line of defense that paying off Stormy Daniels or getting a heads-up from Roger Stone about WikiLeaks wouldn’t be crimes. “They’re testing these messages,” the Republican said. Last night, Mueller was a topic of discussion among the prominent members of Trumpworld, including Don Jr., who gathered at the Trump International Hotel for a birthday party for R.N.C. co-chair candidate Tommy Hicks. “People are speculating that the secret witness in the D.C. court is Don Jr.,” one attendee said. (The White House and a lawyer for Don Jr. did not respond to a request for comment.)