The landmark infrastructure package approved last month positioned Amtrak to pursue entering new cities and to tackle long-delayed maintenance projects. But amid its biggest boost in history, the carrier faces an immediate crisis that threatens service: a scarcity of railroad workers.

Amtrak is struggling to hire and retain workers amid a national labor shortage, down 1,500 people since the start of the coronavirus pandemic. It has left the railroad unable to resume pre-pandemic service levels, expand dining services to some trains or launch long-planned routes.

The intercity passenger railroad is operating about 80 percent of its normal schedule after deep reductions last year. Those levels of service, however, could be reduced next month when the railroad is set to enforce a vaccination policy, which the company says could lead to the termination of 6 percent of its workforce.

Service cuts could be announced weeks after President Biden signed a $1.2 trillion infrastructure bill that puts $66 billion into rail, which Amtrak planned to use for expansion and tackling a backlog of projects. The cash infusion has created the most substantial growth opportunity in Amtrak’s 50 years of existence, coming alongside economic conditions that simultaneously threaten to diminish the system.

“We’ve spent decades trying to get this level of political and public support for train service. Now we have it, and the most immediate way to get the public excited is to add service where it already exists,” said Jim Mathews, president and CEO of the Rail Passengers Association. “We’re not going to be able to do that. And that’s a real shame.”

Amtrak has stepped up recruitment, but acknowledges challenges in finding and retaining workers. The passenger railroad is competing with other railroads to lure experienced train engineers and mechanics, while also looking for cooks, cleaners and other service personnel in a market where hotels and restaurants also are stretched thin.

Freight railroads CSX and Norfolk Southern also say labor constraints are affecting service.

The industry, which cut positions to reshape operations before the coronavirus struck, endured additional staffing reductions during the pandemic. Railroad companies that employed 160,500 people in January 2020 were down to 142,500 last month, according to the U.S. Bureau of Labor Statistics.

“Just as other industries have seen, it’s a tough labor market,” said Jessica Kahanek, a spokeswoman for the Association of American Railroads. In the first six months of 2021, she said freight railroads handled more than 300,000 trailers and containers each week, on average — about 30,000 more than in previous months without major growth in the workforce.

For passenger rail, Amtrak emerged from Thanksgiving week — its busiest since the start of the pandemic — carrying about 600,000 passengers. The railroad estimates it will be at 75 percent of normal passenger levels this month after hitting a low of 3 percent early last year. The public’s return to the tracks is putting more pressure on the company to restore trips.

“We are seeing some impacts of going back to full schedule. If we were fully staffed, we would be able to offer more schedule, where right now we’re unable to do that,” said Qiana Spain, Amtrak’s executive vice president of human resources.

Amtrak said crew shortages have not led to train cancellations as has occurred for some airlines this year. The railroad said it is not promising customers more trips than it can handle.

“We’ve been really monitoring that very closely to make sure that we have the right operational plan,” Spain said.

The potential terminations of unvaccinated workers on Jan. 4 are Amtrak’s most immediate concern. Chief executive William J. Flynn told staff members last month the railroad is preparing for temporary service reductions as about 6 percent of its 17,000 employees were not yet compliant with the policy.

Amtrak has not said where it’s looking at cuts, but industry and labor leaders say the most likely scenario is that some long-distance routes that cross the United States could temporarily go from daily service to three times a week. Rural areas are most likely to be hit, they say, in part because vaccination rates are lower and crews are smaller.

The worker shortage is also threatening the launch of new service that has been in the works for years. In Virginia, officials were expecting two new routes this year — one to Norfolk and one to Roanoke — but said launch dates are postponed until next year.

Haley Glynn, a spokeswoman with the Virginia Department of Rail and Public Transportation, blamed the delay on the nationwide labor shortage, although she said preparation work continues.

“All of the behind-the-scenes work is happening,” she said in late September as Amtrak extended service to downtown Richmond. “But [Amtrak] has had to change the schedules until they get all the labor in place.”

The House Transportation Committee is holding a hearing Thursday on plans for expanding intercity passenger rail.

Industry leaders said despite the labor issues, Amtrak is positioned to continue pursuing plans for expansion and infrastructure improvements with the new federal aid. Some of those projects, including the replacement of old tunnels in the Northeast Corridor, already are in the works, while proposals for new routes are in early planning stages, giving Amtrak years to hire and train workers.

In the short term, replacing key workers — such as locomotive engineers or train conductors — is difficult as safety protocols call for workers who already are familiar with routes to run trains.

John R. Feltz, a railroad division director with the Transport Workers Union of America, which represents mechanics, coach cleaners and waitstaff at Amtrak, said in his nearly 50-year career in the industry he’s never seen such a scarcity of job applicants.

“These are good middle-class jobs. The wages are very good. The benefits are very good. They have railroad retirement, which pays more than Social Security,” said Feltz, a fourth-generation railroad worker. “For some reason, people really don’t want to work the different shifts that we have. They don’t want to work on weekends.”

Most railroad jobs don’t require a college degree but some call for employees to work odd schedules and to be away from home for days. A lead service attendant in a train diner makes up to $70,000, plus tips, while a locomotive engineer earns $100,800. Spain said Amtrak is weighing incentives and new benefits to lure workers and retain existing employees.

The carrier stopped hiring early in the pandemic as it weathered the health crisis, seeing many workers leave as it implemented furloughs, reduced pay and froze retirement benefits. About 520 workers took a voluntary separation offer.

As it restored more train operations this year and brought back pre-pandemic benefits, Amtrak was left scrambling for workers in every part of the company. It has partnered with unions to launch apprenticeship programs and is trying to expedite hiring processes.

But rebuilding the workforce will take time. Engineers, for example, undergo a three-month training at an Amtrak facility in Wilmington, Del., followed by 18 to 24 months of training to be qualified on the territory where they will be operating. Assistant conductors undergo at least a six-month training to be fully qualified.

Amtrak said it is hiring about 200 people for both positions this fiscal year.

Rail advocates say they hope Amtrak figures out the formula to get workers onboard as new rail funding begins to pour in to address a repair backlog, improve stations, replace old trains and create a path to modernize the busy Washington-to-Boston corridor. The infrastructure funding could also overhaul Amtrak’s service map, which has remained nearly unchanged during a period when the nation gained 120 million people. Amtrak’s long-term plan is to bring its trains to 160 new communities.

Mathews said the easiest way to make progress is adding service — a task that’s not possible if the railroad can’t find adequate staff.

“It’s hard to point a finger at Amtrak because they’re just swept up in a national phenomenon,” Mathews said. “And it’s just unfortunate because we’re in a place now where we really need those folks to stay on the trains.”