The fate of thousands of Afghans waiting to reach the United States after serving with American troops was thrown into limbo after President Trump took office. Now military veterans are scrambling to bring as many of them as possible to the country before the administration introduces a travel ban that could restrict their entry.

In an executive order on Jan. 20, Mr. Trump instructed cabinet members, including the secretary of state, to compile a list of countries “for which vetting and screening information is so deficient as to warrant a partial or full suspension on the admission of nationals from those countries.”

The order called for the list to to be completed within 60 days. As that deadline nears, supporters of the Afghan allies have accelerated efforts to bring those eligible to the United States.

“We have been engaged in high-intensity, frenetic work,” said Andrew Sullivan, a military veteran and the executive director of No One Left Behind, a nonprofit whose team has been working marathon days to raise money and arrange flights.

Amid the chaotic pullout from Afghanistan in August 2021, the U.S. military helped evacuate 78,000 Afghans who worked as interpreters and in other capacities during the war. Tens of thousands of others who aided U.S. forces are still trying to reach the United States.

The wartime allies can apply for a Special Immigrant Visa, which allows them to travel to the United States with their families and receive permanent residence. Many have been waiting for months or longer in neighboring Pakistan and in Albania and Qatar to complete processing by U.S. authorities.

In his first term, Mr. Trump barred nationals from seven majority Muslim countries — Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen — from entering the United States. This time, Afghanistan is among the countries whose citizens could be categorically blocked, according to U.S. officials. The officials said that Cuba and Venezuela could also be added.

If Mr. Trump includes Afghanistan in a new travel ban, Afghans who helped the United States could be stranded indefinitely.

After his inauguration, the president also signed an executive order that paused funding for refugee resettlement, suspending travel to the United States for thousands of people around the world who had been screened and approved for entry.

Afghans who had obtained Special Immigrant Visas were not barred from relocating to the United States. But in shutting down refugee admissions, the State Department canceled the contracts that had also covered the costs of transporting the Afghan allies. Suddenly they had to pay their own way, and many could not afford the cost.

“People with visas in their passports saw their pathway to safety stripped away overnight,” said Sonia Norton, advocacy director for No One Left Behind, which is based in Arlington, Va.

The organization’s main role had been to supplement government support by providing Afghan families with loans to buy cars, further their education and adjust to the United States. After the executive orders, it quickly pivoted to an emergency fund-raising campaign.

About 37,000 Afghans, and their families, have been issued Special Immigrant Visas since 2009, when the program began. The Taliban, which rules Afghanistan, regards those Afghans as traitors. Thousands have faced retaliatory violence and hundreds have been killed for assisting the United States, according to a 2022 report by No One Left Behind.

At the time that Mr. Trump signed the executive orders in January, some 1,000 Afghans and their family members had visas to come to the United States. Returning to Afghanistan is not an option for them, Mr. Sullivan said.

“There’s a very real chance that they could get kicked back to the Taliban with a U.S. visa in their passport, and that could be deadly to these allies,” Mr. Sullivan, 38, who was an Army infantry company commander in Afghanistan, said in an interview from Doha, Qatar, where his team was on the ground in recent days.

“If we don’t know what’s going to happen with immigration policy, we’re not going to sit idly by,” he said. “We’re going to come and support them.”

No One Left Behind, established in 2014, has raised millions of dollars in a matter of weeks from veterans and other Americans to buy airplane tickets for Afghan families who had already been cleared to travel to the United States from Albania, Qatar and Pakistan.

Several veteran groups, including Iraq and Afghanistan Veterans of America, have voiced concern for the fate of the Afghan allies.

Three Republican members of Congress said in a letter to President Trump that his executive orders had resulted in the “immediate shutdown” of Afghan relocation efforts. “These are not random applicants or illegal migrants who’ve crossed the southern border,” said the March 4 letter signed by Michael Lawler of New York, Michael McCaul of Texas and Richard Hudson of North Carolina.

“For many Afghans in the pipeline, staying in Afghanistan is a death sentence,” they said.

The White House did not respond to request for comments on the impact of the executive orders or the effects of a potential travel ban on Afghans who supported the U.S. mission.

Aman Jafari, who interpreted for U.S. Navy Seals, arrived in Portland, Ore., from Albania on March 5 with his wife and four young children.

“When Mr. Trump canceled flights, we didn’t have money to book our own flights to America,” said Mr. Jafari, 33. ”We just worried terribly what would happen next.”

Then No One Left Behind stepped in, he said.

On Tuesday, Mr. Sullivan arrived in Los Angeles from Doha to meet potential donors.

Evelyn Moore, 67, who has no military connections, said she had donated to the organization’s effort because Mr. Trump’s policies could have “dire consequences” for those who risked their lives for the United States.

“We must keep our allies on a path to the U.S., as promised,” she said.

By the end of this week, No One Left Behind hopes to have flown to the United States every Afghan who already has a visa.

It must also help them get on their feet in their adopted country.

Mr. Trump’s executive order halted funding to nonprofits like the International Rescue Committee and HIAS, which used to provide services such as rental assistance and job placement to refugees and Afghan allies for at least 90 days after their arrival.

No One Left Behind has partnered with community organizations and volunteers in cities like Portland, Rochester, N.Y., and Sacramento to fill the void.

Mr. Jafari’s family is living in an Extended Stay America hotel outside Portland while he waits for an apartment to be leased for his family. Rent will be paid by No One Left Behind and a local group, the Afghan Support Network, until Mr. Jafari becomes self-sufficient.

“I am so glad that I arrived in America,” he said. “I want to work hard for my family to have a good and bright future.”

Alain Delaquérière contributed research.