It looks like President Donald Trump is going to have a harder time than expected replacing John Kelly as chief of staff.

Nick Ayers, who is currently Vice President Mike Pence’s chief of staff, was reportedly whom Trump had in mind for the job, but the 36-year-old operative is apparently out of the running. He tweeted on Sunday that he would be leaving the White House at the end of the year.

That leaves onlookers — and, apparently, many in the White House — with a big question: If not Ayers to replace Kelly, then who? It’s not clear anyone, including the president, has any obvious answers.

There are a number of names in the mix, though none is the obvious frontrunner: House Freedom Caucus Chair Rep. Mark Meadows (R-NC), Treasury Secretary Steven Mnuchin, Office of Management and Budget Director Mick Mulvaney, and US Trade Representative Robert Lighthizer, according to the New York Times. The Times reports former New Jersey Gov. Chris Christie and former Trump deputy campaign manager David Bossie have also been mentioned. According to Politico, acting Attorney General Matt Whitaker is also in the running.

But of those names, it’s not clear who actually wants the job.

A person familiar with Mnuchin’s thinking told Politico that he is very happy in his current spot as Treasury secretary and thinks that’s where he can be of best use.

In an appearance on CBS’s Face the Nation, Lighthizer signaled he’s not interested in the chief of staff job, telling Margaret Brennan that no one had talked to him about the job.

“I haven’t spoken to anyone,” Lighthizer said. “I’m entirely focused on what I’m trying to do and — it’s difficult enough.”

Politico’s Nancy Cook reported that Mulvaney is also no longer interested in the job. CNN reports Meadows has said he’s “absolutely not” interested in the chief of staff job.

Being hesitant to take on the chief of staff role is understandable. The Trump White House is notoriously chaotic, and the president has a volatile personality.

Kelly and Trump’s first chief of staff, Reince Priebus, didn’t exactly exit on the best of terms. Trump announced Priebus’s exit in a tweet. Before Kelly’s departure was revealed, he and Trump were reportedly no longer speaking. Kelly was supposed to announce he was leaving at a staff meeting on Monday, but Trump preempted him, telling reporters on Saturday that Kelly was leaving.

The Times reports that Ayers and Trump couldn’t agree on the terms of his tenure — Ayers had told the president he would serve in an interim capacity through the spring, and Trump wanted him to stay on longer. Ayers plans to return to his home state of Georgia, where he could potentially run for office, and perhaps did not want to run the risk of his reputation being marred by a tumultuous tenure in the Trump administration.

Still, the president continues to insist all is well. He tweeted on Sunday that he’s interviewing “some really great people” for the chief of staff job and will make a decision soon.

I am in the process of interviewing some really great people for the position of White House Chief of Staff. Fake News has been saying with certainty it was Nick Ayers, a spectacular person who will always be with our #MAGA agenda. I will be making a decision soon! — Donald J. Trump (@realDonaldTrump) December 10, 2018

Trump is finding out this presidential staffing thing isn’t so easy

The news that Trump is on the hunt for a third chief of staff less than two years into his administration prompted callbacks to his 2012 tweet in which he criticized then-President Barack Obama for turnover in his administration at the chief of staff level.

3 Chief of Staffs in less than 3 years of being President: Part of the reason why @BarackObama can't manage to pass his agenda. — Donald J. Trump (@realDonaldTrump) January 10, 2012

As Vox’s Dara Lind points out, Obama did have unusually high turnover in the chief of staff spot during his first term, but “Trump will have to hold on to his next chief of staff for over a year not to beat Obama’s pace.” And given the high burn rate in the Trump administration, that might be a heavy lift:

Working in the White House is a high-stakes job, and even more so in the Trump administration, with all the backstabbing and volatility. Trump has diminished the positions and personalities around him, often tweeting criticisms of his own appointees and contradicting members of his administration. It makes sense that anyone in the running to become his next chief of staff would want to give it some serious thought.