The man with the biggest portfolio on Capitol Hill will be stepping down at the end of November. Architect of the Capitol Stephen T. Ayers will be leaving his post after ascending to the top job over a 20-year career with the agency.

The architect of the Capitol oversees the upkeep and preservation of more than 17.4 million square feet of facilities and 580 acres of grounds on the Capitol campus. That includes the historic House and Senate office buildings, the Capitol itself, thousands of works of art and even the trees that dot the campus.

The search for candidates to fill Ayers’ role is underway, but it could be a lengthy process.

While the architect is appointed by the president and subject to Senate confirmation, the president cannot pick anyone he wants. Of all the previous executives, President Donald Trump might be the one with the most experience with architects, but it is unlikely that a connection from his real-estate portfolio will be nominated.

A bicameral and bipartisan congressional commission must be assembled to recommend candidates to the president. Trump will only be able to nominate a name from that select list.

The commission is made up of 14 lawmakers, including the speaker, the president pro tempore, majority and minority leaders of both chambers, and the chairs and ranking members of the House Administration and Senate Rules committees and the Appropriations panels in both chambers.

The to-do list for the postelection lame-duck Congress is lengthy, and before they left for the midterm recess, lawmakers were not sure whether the commission would be assembled before the new Congress. Speaker Paul D. Ryan and House Administration Chairman Gregg Harper of Mississippi and ranking member Robert A. Brady of Pennsylvania are retiring, meaning three new faces would join the commission.

The process of selecting a new architect of the Capitol can drag on for years. The previous AOC stepped down in February 2007, and a list of candidates, including Ayers, was sent to President George W. Bush that August.

In October, Kemel Dawkins, the vice president for campus services at Duke University, asked that his name be taken off the list, throwing a curveball into the process. It was not until February 2010 that President Barack Obama officially nominated Ayers, and the Senate confirmed him that May.

Back in 2008, when Ayers was acting architect, Roll Call asked him what a good candidate for the AOC job needed to possess.

The new architect — whoever that might be — must be a strong leader who knows both facilities management, historic preservation and architecture, he said.

“It has to be someone that has been in that kind of role and has been in that position before,” Ayers said. “Someone who is a great communicator, who can partner and work with the Congress.”

A decade later, that’s still the case. A new architect will take over the massive rehabilitation of the Cannon Building, the Senate parking garage project and countless smaller projects that are already underway.

The AOC’s deferred maintenance and capital renewal backlog is estimated at $1.376 billion.

“AOC employees are in a race against time as the infrastructure rapidly deteriorates and projects continue to accumulate,” Ayers told lawmakers earlier this year.

Candidates for the architect role will have to be ready for a hallmark of public service — a significant pay cut. The architect of the Capitol makes an annual salary of $172,500, which can be well below what private-sector architects with years of experience usually bring home.

Former AOC employees told Roll Call that the pay scale and intense scrutiny of congressional oversight could make highly qualified candidates think twice.