Two Vietnamese brothers who petitioned to travel to the United States to donate bone marrow to their dying brother in San Jose were denied temporary visas by the U.S. government, according to the family.

“We don’t know what to do,” said Trinh Colisao, 33, whose father, Tu Le, has an aggressive form of blood cancer. “At this point we’re just hoping to get his story out.”

Le’s brothers in Vietnam, Lam Le and Hiep Nguyen, applied for B-2 tourist visas at the end of May, citing a medical emergency. They were denied entry on June 3, Colisao said.

An immigration official from the U.S Consulate in Vietnam called the brothers individually to let them know they didn’t qualify for the visas, but did not provide further explanation, Colisao said. The pair has not received any documentation from the government detailing why their applications were denied, she said.

Tu Le, 63, was diagnosed in January 2018 with Myelodysplastic syndrome, which occurs when the blood-forming cells in the bone marrow become abnormal. A U.S. citizen and father of four, he needs a bone marrow transplant to survive, Colisao said.

No one on the donor list matched Tu Le, so the family turned to relatives in Vietnam, she said. Stanford Health Care, which is involved in Tu Le’s care, sent test kits to the brothers and other family members.

It’s extremely rare to find a perfect match, and, in this case, critical for Tu Le’s survival, a Stanford doctor caring for Tu Le said in a letter to the U.S. government. Both brothers are a 100% genetic match.

The family has reached out to Sen. Kamala Harris, D-Calif., and Rep. Zoe Lofgren, D-San Jose, in hopes that they’ll intervene.

“It's unconscionable that Tu Le is being denied his best chance to receive the lifesaving treatment he needs,” Lofgren said Thursday. “My office is currently working with Tu and his family to help however we can.”

A representative for Harris declined to comment.

The State Department, which processes B-2 tourist visas that also cover trips for medical purposes, refused to confirm the family’s account, citing confidentiality laws.

“We cannot discuss the details of individual visa cases,” a spokesperson said in a statement. “Whenever an individual applies for a U.S. visa, a consular officer reviews the facts of the case and determines whether the applicant is eligible for that visa based on U.S. law. Consular officers refuse visa applications if an applicant is found ineligible under the Immigration and Nationality Act or other provisions of U.S. law.”

To qualify for a visitor visa, individuals must submit an application and a photograph, have a valid passport, and complete an interview at the embassy or consulate in the country they live in, according to the State Department website. Immigration authorities may request further information or documentation during the interview, such as the reason for the trip, an intent to leave the U.S. after the trip and ability to pay trip costs.

Approvals of visitor visas have declined in recent years — an estimated 32,400 B-2 visas were approved in 2018, compared with 42,000 in 2017; 43,500 in 2016; 63,400 in 2015 and 126,500 in 2014, according to State Department data.

Colisao, of San Jose, said she believes the fact that her uncles live in a communist country — and have no concrete evidence to prove they’d return to Vietnam after the transplant — influenced the government’s decision.

“I feel like the current political climate that we’re in is not very supportive of people from those countries visiting the U.S., even for humanitarian reasons,” she said.

Tu Le immigrated to the U.S. in 1992. He and his wife, Melody Bui, later became U.S. citizens. Today, Bui cares for Tu Le full time in the couple’s San Jose home.

In a May 21 letter submitted to the U.S. Consulate in Vietnam with the brothers’ visa applications, Tu Le’s physician at Stanford Health Care, Laura Johnston, wrote about the urgent need for a bone marrow transplant to save his life.

“Of the nine potential donors, only two are a perfect match,” the letter said. “Using a perfect match will improve chances for a successful transplant and reduces risk of complications.”

Without a transplant, Tu Le’s cancer will advance quickly, and he would only have a few weeks to live, his daughter said.

The brothers will attempt to apply for humanitarian parole, “an extraordinary measure sparingly used” that allows an otherwise inadmissible individual to temporarily enter the U.S. due to a compelling emergency, according to U.S. Citizenship and Immigration Services.

“It’s really rare, because it’s not sought after that often compared to other types of entry to the United States,” said Bill Hing, a law professor and director of the Immigration and Deportation Defense Clinic at the University of San Francisco, said of humanitarian parole. “Because it’s not sought that often, the State Department and Department of Homeland Security are unfamiliar with the process.”

But Hing, who has successfully helped two clients get humanitarian parole — both to visit dying relatives in the U.S. — says the family has a chance.

If they’re denied, Colisao said the family will consider a donor who isn’t a perfect match, though it would diminish Tu Le’s chances of a successful transplant. One potential risk is graft versus host disease, when the immune cells from the donor attack the recipient’s cells, according to Stanford.

The family can’t afford to send Tu Le to Vietnam or another country where they can perform the transplant.

“We now have to consider these risky, risky options for my dad because we don’t have any other option,” Colisao said. “Time is of the essence.”

Tatiana Sanchez is a San Francisco Chronicle staff writer. Email: tatiana.sanchez@sfchronicle.com Twitter: @TatianaYSanchez