Blame Congress. Blame the airline industry. Blame sequestration. But Washington Dulles International Airport is in trouble. The most alarming evidence: Sometime next year, more passengers will travel through Reagan National Airport than Dulles — an airport 14 times National’s size.

For Virginia leaders, as well as the agency that manages both airports, it is a deeply troubling development. Should National continue to outpace its larger neighbor, it could have serious financial and safety implications for the entire region, they say.

A recent study found that Dulles generated more than $1.2 billion 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.

“The shift to National — it’s a serious problem for the financial viability of Dulles,” said Jonathan Gifford, director of the Center for Transportation Public-Private Partnership Policy at George Mason University.

The MWAA needs both airports to succeed for its bottom line, but in its version of a perfect world, Dulles would be booming. Instead, the explosive growth at National is creating headaches for the authority. From a steep rise in noise complaints from nearby Arlington County residents to concourses so crowded that passengers say they feel like sardines, authority officials are scrambling to find more space at a facility that has little to spare.

The opposite is happening at Dulles, where a slowdown in domestic traffic has touched off concern about the airport’s viability. Dulles has long been billed as the region’s international hub, but recent days have been unkind to the airport. Although the number of international flights has grown significantly (Air China and Brussels Airlines are among the international carriers that launched service this year), analysts say that the steady erosion of domestic connections could prompt some carriers to move their business to other hubs such as Newark Liberty International and John F. Kennedy International airports, which offer passengers more domestic connections.

Few regions in the country have such ready access to three major airports. In addition to Dulles and National, travelers in the Washington area can opt for Baltimore-Washington International Marshall, which remains the region’s top airport for passenger traffic — in large part because of the significant presence of low-cost carrier Southwest Airlines.

In 2013, 22.5 million passengers flew through BWI, compared with 21.9 million at Dulles and 20.4 million at National.

Among the three, though, Dulles seems to suffer the most from the perception that it is a hassle to use.

A recent online list of “35 Things You’ll Never Hear a Washingtonian Say” by Time Out Washington took a poke at the airport: “No. 7: ‘Well, if the flight getting into Dulles is $10 cheaper, then let’s do that one.’ ”

Rob Quartel, chairman and chief executive of Ntelx, a technology company in Tysons Corner, travels frequently for his job. But he said that even though his office is in Tysons, he would rather fly from National (18.1 miles away) to a connecting flight at the Newark airport than start at Dulles (16 miles away) to reach his international destination.

“Dulles is a long way away, even from Tysons,” he said. And just the thought of hopping aboard one of the airport’s mobile lounges “makes my blood boil.”

A Delta Air Lines jet takes off from Reagan National Airport. The airport’s passenger count has grown in recent years while numbers at Dulles have declined. (Manuel Balce Ceneta/ AP)

And then there’s Bob Arias, of Crownsville, Md., who said that when it comes to international travel, he’d rather drive to Philadelphia International Airport.

“There is inexpensive off-site parking,” he said. “There are nonstops to many European destinations and connections in Europe to just about anywhere. For me, the drive is only 30 minutes more than [Dulles], but the gates are closer and the security hassles are much less.”

Airport officials think Dulles’s problems are temporary. The travel market is cyclical, they said, and Dulles will rebound.

“The future of Dulles is bright,” said Jack Potter, MWAA president and chief executive. But the present, he conceded, is not as rosy. Officials project that 22.7 million passengers will fly through National next year; only 20.7 million are expected to fly through Dulles.

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 that planes can fly. The strict rules were part of an effort to fuel growth at Dulles, and for years, they worked. Flights of longer than 1,250 miles were prohibited at National, pushing travelers who wanted nonstop options to the West Coast to Dulles.

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

Those actions have siphoned significant numbers of passengers from Dulles. Between 2011 and 2013, Dulles lost nearly 200,000 seats to National, authority officials say.

Take JetBlue. In 2008, it had 24 flights a day out of Dulles. Today, it has six. The airline has migrated most of its operations, including maintenance, to National, where it offers 30 flights daily.

And while the airline would never close the door on expanding service at Dulles, Scott Laurence, JetBlue’s senior vice president of planning, said such a move doesn’t make business sense.

The MWAA’s biggest fear is that in the upcoming reauthorization process to fund the Federal Aviation Administration, Congress might scrap the restrictions on flights at National altogether, a scenario they say could have dire consequences for Dulles. In 2009, Sen. John McCain (R-Ariz.) floated such a proposal, arguing that the increased service would lead to lower prices and more choices for consumers. Opponents, however, were quick to note that US Airways, which has a large presence at National and has since merged with American Airlines, was based in McCain’s home state.

Virginia politicians, including retiring Rep. Frank R. Wolf (R) and Sen. Mark R. Warner (D), fought the effort and continue to believe that changes to the rules are short-sighted.

“Northern Virginia’s economy is strongest when both major airports are in a position to thrive,” said Sen. Timothy M. Kaine (D), the state’s junior senator. “It does not make sense for Reagan National, with an area of 860 acres, to be on pace to have more travelers passing through it than Dulles, which comprises 12,000 acres. I am committed to working with Senator Warner to urge our colleagues not to include new slot exemptions at Reagan National Airport in the next FAA reauthorization.”

There are, however, other reasons Dulles has foundered. Airline mergers and a general decline in domestic passenger traffic have hurt the airport. For years, Dulles benefited from its proximity to the nation’s capital, where government workers provided a steady stream of customers. But sequestration, the automatic budget cuts that went into effect in 2013, forced many federal agencies to cut their travel budgets. At a briefing this summer, an official with United Airlines, which accounts for about 65 percent of the flights at Dulles, said it lost a “rock solid” 10 percent of its traffic due to sequestration.

According to statistics from the Metropolitan Washington Council of Governments, among those who lived in the D.C. region, 40 percent said they traveled for business in 2011; by 2013, that number had dropped to 27 percent.

In the late 1990s, airport officials invested more than $5 billion in new projects with an eye toward the future, including an Aerotrain system that was designed to replace the cumbersome mobile lounges, new parking garages and a new runway. Even after the Sept. 11, 2001, terrorist attacks, passenger traffic at Dulles continued to grow. In 2006, Dulles had its best year ever, with 27 million passengers passing through the airport. But passenger traffic has declined every year since then.

Airport officials say they have done their best to boost traffic, offering incentives to attract more people to the airport and get them to spend more once they arrive. Dry-cleaning and other special programs have been added for frequent travelers. New high-end shopping and dining options, including Montblanc and a branch of the District Chophouse, have been added. The MWAA also won permission from the FAA to add such amenities as a second hotel and a gas station to generate more revenue.

A new agreement with the airlines, which the MWAA board approved this month, will for the first time allow the MWAA to share revenue between the two airports. It also would require airlines to compensate the authority if Congress opens the door to more long-distance flights out of National.

Metro’s new Silver Line also could give the airport a boost. The second phase of the $5.6 billion rail line, expected to be completed in 2018, will include an airport station.

“The Silver Line is a selling point for Dulles,” said Kenneth Button, director of George Mason’s Center for Transportation, Policy, Operations and Logistics. “It will make the airport look more linked in to the world.”

MWAA officials also have launched an aggressive lobbying campaign, urging community members, local officials and others on the Hill to push Congress to keep the rules in place.

“Ultimately, it may be ­self-correcting,” said George Mason’s Gifford. “Dulles is not going to move. The runways and terminals — that stuff is in the ground, and it is not going anywhere. It may be that looking back, some of those major capital investments should have been delayed or scaled back, but what’s done is done, no one is going to go out there and pull out a runway.”

Scott K. York (R), chairman of the Loudoun County Board of Supervisors, said the launch of nonstop service to Beijing by Air China and the start of daily service by budget carrier Frontier are reasons to be hopeful about the airport’s future.

“There are obviously a few clouds over Dulles, but I also see a bit of sunshine,” he said.