Nick Ayers could almost be confused for a college fraternity brother as he flashes a broad grin in a selfie taken with Mike Pence just moments after the Indiana governor was named Donald Trump's running mate. In fact, the baby-faced campaign strategist in the white undershirt had a pivotal role in Mr. Trump's selection of Pence in 2016. And two years later, Ayers' bond with Pence is stronger than ever, as are his ties to the president.

A seasoned campaign veteran at age 36, Ayers is emerging as a leading contender to replace White House chief of staff John Kelly, whose departure has long been the subject of speculation.

If selected, Ayers would return a political mind to the role as Trump's presidency enters a new, more perilous phase in which he fights for re-election while fending off new oversight efforts from a Democratic House.

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In any administration, the role of White House chief of staff is split between the responsibilities of supervising the White House and managing the man sitting in the Oval Office. Striking that balance in the turbulent times of President Trump has bedeviled both Kelly and his predecessor, Reince Priebus. If Ayers becomes the third person to tackle the job, it'll be his most significant challenge — and one friends say he's well-equipped to handle.

"He manages up as well as anyone I've ever seen," said Phil Cox, a former colleague at the Republican Governor's Association who bought Ayers' political consulting business earlier this year.

Vice President Mike Pence's chief of staff Nick Ayers (L) and National Security Adviser H.R. McMaster arrive in the Rose Garden on Oct. 23, 2017, in Washington, D.C. Getty

Mr. Trump is said to have warmed to Ayers in part by watching the effectiveness of Pence's largely independent political operation. The vice president's chief of staff for the last 18 months, Ayers has earned the backing of Ivanka Trump and Jared Kushner, the president's daughter and son-in-law and senior advisers, for taking on the new role, White House officials said.

Ayers would be the youngest chief of staff since 34-year-old Hamilton Jordan served under Jimmy Carter.

But before Ayers can have his crack at leading the White House staff, he first has to overcome opposition from some who may soon work for him.

On Air Force One on Sunday as Mr. Trump returned to the U.S. from a turbulent two-day trip to Paris, aides argued to the president that Ayers was the wrong person for the job, according to two people familiar with the matter, The Associated Press reports. More than a half-dozen administration aides spoke about Ayers on condition of anonymity to discuss the sensitive personnel matter, the AP reports.

In some corners of the White House, Ayers is viewed skeptically over how he has led Pence's office, which operates largely independent of the Trump West Wing. Some in the White House blame Ayers for planting news stories critical of the administration or its strategies, while others have complaints about his efforts to circumvent the president's political operation. Some aides have taken to calling him "Tricky Nicky."

Ayers didn't respond to a request for an interview from The Associated Press. But allies said he is eager to take on the chief of staff job. He and Mr. Trump have been discussing the possibility of making the switch for months.

Allies said that while Ayers isn't as deeply versed in foreign policy as some of his predecessors, he had developed experience advising Pence on global affairs. He has been a frequent participant in Mr. Trump's daily intelligence briefings, occasionally even when Pence wasn't present.

The timing of Kelly's expected departure isn't clear, though White House aides predict it will occur in tandem with the anticipated exit of Homeland Security Secretary Kirstjen Nielsen in the coming months. Sources familiar with the matter told CBS News Nielsen will be leaving, but say the timing is uncertain. Just last month, Mr. Trump praised her response to devastating hurricanes, and she has been a vocal advocate for the president's policies, including immigration.

But sources said she could fall victim to the president's frustration that his immigration agenda has stalled.

However, senior White House adviser Kellyanne Conway attempted to cast doubt Tuesday on the anonymously sourced reports about a staff shake-up.

"Why do they remain anonymous? Could it be that it's not completely verified and true?" she said.