An employee at Dulles International Airport looks out a window at the airport in this file photo. (Matt McClain/The Washington Post)

Dulles matters.

That was the message Thursday at an event that was part pep rally, part strategy session and all about turning around the troubled fortunes of Dulles International Airport.

Virginia Gov. Terry McAuliffe (D) opened the conversation about the airport’s future with the trademark energy he seems to bring to all things Virginia.

“I am a huge advocate for Dulles Airport,” he told the crowd of more than 300 people gathered at the AOL campus in Loudoun County. McAuliffe then ticked off a long list of ways the state has benefited from its presence. Because of Dulles, for example, it’s easier to lure such major companies as Raytheon and Lockheed Martin to the state and ensure that Virginia’s wines are stocked on shelves in Paris, he said.

At the same time, McAuliffe acknowledged that the airport has fallen on tough times. Fewer people are choosing to fly through Dulles, and it is struggling to pay off billions in debt from aggressive expansion plans that have been curtailed, leaving the airport with a half-finished feel.

Virginia’s political and business leaders are desperate to reverse the passenger declines that have plagued Dulles as regulatory changes — some call them congressional interference — have pushed more passengers to Reagan National Airport.

In 2005, 27 million passengers flew through Dulles; last year, that number was 21.6 million. By comparison, 17.8 million passengers flew through Reagan in 2005. By 2014, that number had grown to 20.8 million.

Still, despite National’s growth, Baltimore-Washington International Thurgood Marshall remains the region’s busiest airport, with 22.3 million passengers in 2014.

But there are others who argue that airport officials created their own problems at Dulles by expanding too quickly and creating a facility that some travelers find too difficult to navigate.

“This is an event for boosters,” said Stewart Schwartz, executive director of the Coalition for Smarter Growth, referring to Thursday’s event. “Nobody’s asking the hard questions — like, ‘Did they overestimate demand and take on too much debt?’ ”

Schwartz said that although Dulles is a key regional asset, the public must be sure its leaders are making the smartest choices when it comes to spending taxpayer money.

Wherever the fault may lie, however, Virginia leaders say they can’t afford to let the airport founder.

A recent study found that Dulles generated more than $1.2 billion a year in tax revenue and nearly $10 billion in labor income. More than 19,000 people work at Dulles, but nearly 250,000 jobs are tied to the airport, according to the study, commissioned by the Metropolitan Washington Airports Authority. MWAA operates National and Dulles.

The shift in passenger traffic is so pronounced that at some point this year, National is expected to serve more passengers than Dulles, an airport that is 14 times as large.

Still, there are small signs that Dulles’s fortunes may be improving.

Jack Potter, the chief executive of MWAA, said fears that Southwest Airlines might leave Dulles to focus on its operations at National have proved unfounded. And officials are predicting a slight boost in passenger traffic this year. But it was clear from those gathered Thursday that there will be no easy — or quick — fix.

The biggest immediate challenge Dulles faces may be on Capitol Hill as Congress moves this year to reauthorize funding and set priorities for the Federal Aviation Administration, Potter said.

MWAA officials blame many of Dulles’s woes on Congress and its tinkering with decades-old rules that limit the number of takeoffs and landings at National as well as the distance planes can fly nonstop.

The strict rules were part of an effort to fuel growth at Dulles. Flights of longer than 1,250 miles were prohibited at National, pushing travelers who wanted nonstop options to the West Coast to go to Dulles.

But since 2000, members of Congress — many from Western states — have weakened the rules, allowing 26 additional round-trip flights, including 18 “beyond-perimeter” flights to cities including Phoenix, Salt Lake City, San Francisco and Denver.

Sen. Timothy M. Kaine (D-Va.) is among those who worry that some of his colleagues will once again push for more long-haul flights to be allowed at Reagan. Or worse, push to scrap the perimeter rule all together.

“It’s not hard to figure out what the challenge is,” Kaine said. “There are 535 members, and only 13 of those are Virginians. The 13 in Virginia are going to battle like hell to maintain the perimeter rules, but the rest? The rest want to fly home as fast as they can.”

Still, Kaine thinks that the battle can be won with the right strategy, one that includes emphasizing the importance of Dulles’s international reach.

Rep. Barbara Comstock (R-Va.) said she thinks the delegation can make the case that there have been too many changes at National and that it’s time to take a breather.

“We’ve made an investment here in Dulles and in Dulles rail, and it’s an investment we need to have supported on a national level,” Comstock said.

Phase 2 of Metro’s new Silver Line will include a station at Dulles.

“We need to rally and put Dulles and this region onto a positive growth path,” said Keith Meurlin, president of the Washington Airports Task Force, one of the sponsors of Thursday’s program.

“It’s time to get back to basics,” he added. “We must all be prepared to make the hard decisions to ensure the region and Dulles continue to grow.”