WASHINGTON — A group of Democratic senators on Thursday called on the Biden administration to account for what they said was “disparate” treatment of Afghans who have sought to flee their country since the U.S. withdrawal compared with Ukrainians fleeing the Russian invasion.

President Joe Biden’s recent creation of a program to ease a pathway to the United States for Ukrainian war refugees cast the administration’s more restrictive policy toward Afghans and others into “stark” relief, Democratic Sens. Ed Markey of Massachusetts, Jeanne Shaheen of New Hampshire, Patrick Leahy of Vermont, Cory Booker of New Jersey, Ron Wyden of Oregon and Elizabeth Warren Massachusetts wrote in an open letter to Biden and the Department of Homeland Security on Thursday.

“While the U.S. response to the Ukrainian refugee crisis has been admirable, it is unfortunate that this welcoming and accommodating model is not the standard for all humanitarian crises, wherever they occur, whether in Haiti, throughout Central America, in Africa, the Pacific, and elsewhere,” the senators wrote.

The Uniting for Ukraine (U4U) program, created last month, allows Ukrainians to apply for temporary refuge, known as humanitarian parole, in the United States if they meet certain basic criteria, including that they lived in Ukraine at the time of the Russian invasion and that they have a U.S.-based sponsor to vouch for them. The Russia invasion of Ukraine began in February.

Since the U4U program launched last month, “nearly 22,000 Ukrainian nationals have been authorized to travel to the United States to apply for parole,” said Angelo Fernández Hernández, a spokesman for the Department of Homeland Security.

While refugee advocates have applauded the program for its humanitarian breadth, it has also been criticized by several American veterans groups, refugee resettlement organizations, and Afghan advocates, who say the administration has simultaneously hindered tens of thousands of Afghans from seeking refuge the same way. The United States in late August completed its withdrawal of troops from Afghanistan.

Administration officials say the comparison is unfair. The Biden administration last year brought more than 76,000 Afghan evacuees to the United States, most as humanitarian parolees, after a chaotic August withdrawal ushered in the collapse of the U.S.-backed government and the return of Taliban control.

Two thousand more Afghans have followed in the months since, and Operation Allies Welcome, as the government has called the mass resettlement effort, represents its own “separate pipeline to welcome our Afghans allies,” said a senior official, who spoke on the condition of anonymity in accordance with guidelines set by the administration.

Afghans and Ukrainians who come to the United States through these programs are allowed to stay for up to two years before they must apply for a more permanent immigration status. They are eligible to receive temporary work authorization during that time, and the Afghans are also able to access temporary housing support and other cash and resettlement assistance, whereas the Ukrainians are not, said Fernández Hernández.

The Ukraine program is “quite different in a way, in that it’s not set up for permanent relocation to the United States. It’s meant to be kind of a safe harbor program, which is different from Afghans, because I don’t think any of us expect Afghans who flee to go back to Afghanistan any time soon,” the official said.

Critics of the U.S. handling of its Afghanistan withdrawal say that despite the mass airlift, tens of thousands of Afghans - including those who worked directly for and alongside the U.S. government - were left behind and have struggled to find a way out. The U.S. government concedes there is no easy way to get Afghans out of their country.

The senior official said the administration would like to see more Afghans moved to the United States but that “it is very difficult for people to get out of Afghanistan if it is not facilitated by us. So that’s a key difference, that under United for Ukraine, you can book a commercial flight.” Afghans can’t.

More than 40,000 Afghans have applied for humanitarian parole through U.S. Citizenship and Immigration Services, a division of Homeland Security, for lack of other viable escape routes. The Taliban has enacted a harsh new government and detained or assassinated people associated with the previous American-backed system, lawmakers and advocates say.

For humanitarian parole applicants, there are formidable hurdles, including a per-person application fee that exceeds what the average Afghan earns in a year and a requirement to prove that they’ve been personally targeted by the Taliban. The creation of Uniting for Ukraine has, meanwhile, offered Ukrainians a path to humanitarian parole with no such burdens.

Ukrainians applying for humanitarian parole through U4U are not required to show any proof of individualized targeting - only that they were displaced because of the war.

The Department of Homeland Security says that 70 percent of Afghan parole applicants remain in Afghanistan, which means the United States will not process their applications because it cannot vet or interview them in person.

The lawmakers say the Biden administration can try harder.

That the Biden administration has delivered billions of dollars in aid and rallied the world in support of Ukrainians “proves that when we have the will, we will find a way to live up to American ideals of embracing people fleeing war and oppression,” Markey said in a statement. “My question is why this approach is reserved for a select few, when refugees from Afghanistan and around the world facing persecution, instability, and violence face barriers to entry that Ukrainians get to bypass.”

“It’s a shameful but well-documented reality that, throughout our history, the United States has prioritized the comfort and safety of European Christian migrants,” Markey said.

In just over a month, the administration has approved 6,000 Ukrainians for humanitarian parole through the program. But the vast majority of Afghan parole applicants have languished with no answer, the senators wrote in their letter. Of those who saw their cases adjudicated: “The United States has approved only 270 Afghans for humanitarian parole, denying more than 2,000 applications,” they said.

While Biden has raised the annual cap on refugees allowed to resettle in the United States - his administration has not actually admitted that many refugees in practice, the senators said. “[O]nly 3,268 refugees were resettled” in the United States between Oct. 1 and Dec. 31 - putting it on track to resettle only 10 percent of the 125,000 refugees Biden said the United States aims to welcome.