After 18 months on the job as President Trump's chief of staff, reports erupted last week that John Kelly would exit the White House within days. As with many of Trump's closest aides, rumors of conflict abounded: The two men apparently had stopped speaking to one another, and the decision for a departure would be mutual. When Trump confirmed the change, he thanked Kelly for his service, carefully avoiding the term "fired," but not quite resisting the opportunity to add, "I don't know if I can say 'retiring.'"

On paper, the transition plan looked smooth. But let's be honest: Few things have gone smoothly for the Trump administration. Even its successes have been hard-fought and rocky. Now, it appears Kelly's departure has triggered more chaos.

For months, observers expected Vice President Mike Pence's chief of staff, Nick Ayers, to succeed Kelly. Despite only being 36 years old, Ayers has been in national politics for more than a decade. At 25, he served as executive director of the Republican Governors Association, and at 28 he was named to Time magazine's "40 under 40" list for 2010. Pence tapped him as national chair of his 2016 campaign. Ayers clearly has big political ambitions, for which taking on Kelly's job was the next obvious step.

Instead, Ayers suddenly took himself out of the running. A planned announcement on Monday naming Kelly's successor had to be canceled when Ayers reportedly told Trump that he'd only agree to do the job transitionally. Trump tweeted out Sunday that it was "fake news" that Ayers had taken the job, and that he was interviewing "some really great people" for the position. The Wall Street Journal reported that Trump's budget chief and top fixer Mick Mulvaney and Freedom Caucus leader Rep. Mark Meadows (R-N.C.) were among the top contenders.

However, Mulvaney also reportedly withdrew immediately, leading some to wonder whether anyone would want the job — or why. After all, as Politico's Eliana Johnson and Alex Isenstadt wrote, the chaos and public rebukes generated by Trump have turned the chief of staff role into a "laughingstock." With Robert Mueller's special counsel investigation presumably nearing its end, and a new Democratic House eyeing investigations of the White House, the job of keeping Trump on message and on task may well become "mission impossible," according to Chris Whipple, who wrote a book about White House chiefs of staff. "Worst-case scenario," Whipple warned, "you could become H.R. Haldeman, who went to jail for 18 months after participating in Richard Nixon's cover-up."

As Trump's top gatekeeper, Kelly certainly struggled to bring discipline to the White House. The first six months of the presidency produced chaos; the first chief of staff, Reince Priebus, did not have the personal standing to impose order and authority on Trump's inner circle. Kelly firmly established himself as a top dog, second only to Trump himself, but the president reportedly chafed at the discipline, and a few inner-circle denizens made their displeasure known when they found themselves locked out thanks to Kelly's command structure.

Still, Trump and Kelly managed to stick together for a nearly typical tenure for presidential chiefs of staff. Former President Barack Obama had two chiefs of staff in two years as well, and three in his first term. The late George H.W. Bush had three in his single term. Given the media focus on the chaos in the first months of Trump's term, Kelly's relative longevity provides a testimony to his abilities, and to Trump's recognition of the value of Kelly's approach.

For his next chief of staff, Trump might have a limited range of contenders. Even so, his choice will reflect how Trump sees the next two years as he approaches his re-election campaign. Does he look for an opportunity to partner with Democrats on a few key issues to demonstrate his flexibility? Or does he go all-in on gridlock to force voters to choose the nation's direction?

If it's the latter, tapping Meadows would make some sense for Trump. Taking the job would make sense for Meadows, too: Now that Republicans have lost control of the House, the Freedom Caucus will have much less influence on the shape of legislation and policy, so there's little reason for Meadows to stick around. The GOP's leverage will come from the Senate rather than in the House's conservative caucus, and Meadows will have much more power as chief of staff. If Trump wants to set up the next two years as a political fight for the 2020 election, Meadows would bring the necessary hard-ball approach.

But if Trump wants to find ways to reach accommodations with Democrats on issues like infrastructure and health care, Meadows won't be much help. Trump would be better off looking for a moderate Republican, perhaps one who retired from the House or Senate, or lost last month in the midterms. The big question is whether a moderate Republican would want to work in the political cauldron of Trump's White House — and whether he or she would last long enough in that crucible.