The State Department has dramatically ramped up the approval of resettlement visas for Afghan military interpreters this year under a program that a bipartisan group of lawmakers is seeking to extend and expand, arguing that the system has failed many linguists who remain in mortal danger.

Under a bill that members of the House and Senate plan to introduce Thursday, the Afghan Special Immigrant Visa program, which is set to stop receiving applications this fall, would continue to run until the end of 2015 and be open to 3,000 additional petitioners.

The legislation would enable Afghan interpreters who have been approved for resettlement to immigrate with parents, siblings and adult children who can independently demonstrate that they are in danger. Afghans who worked for American news outlets and nongovernmental organizations, as well as those who worked for U.S. troops but were nominally paid for by the international military coalition, also would become eligible for resettlement if the bill becomes law. Those criteria also applied to Iraqi interpreters.

As the U.S. military draws down this year, lawmakers say they feel compelled to do more to help Afghans who are under threat for their work on behalf of the United States.

“We have frankly fallen short of the mark,” said Rep. Earl Blumenauer (D-Ore.), who is sponsoring the House version of the bill with Rep. Adam Kinzinger (R-Ill.), a former Air Force pilot who served in Afghanistan. “It is clear that these people are at risk and that the situation is likely to get worse rather than better.”

Sens. John McCain (R-Ariz.) and Jeanne Shaheen (D-N.H.) are leading the effort in the Senate. Lawmakers and several U.S. veterans of the Afghan war have assailed the State Department and other agencies involved in processing the visas, saying that the program has been beset by years-long delays, arbitrary rejections and opposition from some senior officials who have argued that the program is accelerating Afghanistan’s brain drain.

“America is going to have to go to war again someday, and there is nothing more important than the ability to follow through on our word,” Kinzinger said in an interview.

Earlier this year, Congress demanded that the State Department start releasing data each quarter disclosing how many applicants have been rejected, the number of rejections at each step of the process and the reasons for delays in cases that have been in the pipeline for more than nine months.

Additionally, changes to the program codified in the National Defense Authorization Act, signed into law in January, now require that the State Department explain in a letter its rationale for each rejection. In the past, after waiting for years, some applicants received bare rejection forms that branded them as security threats.

Marie Harf, a State Department spokeswoman, said in an e-mailed statement that the department has made significant strides in processing visas for Afghan interpreters in recent months by streamlining each step. This year, the State Department has issued more than 1,600 visas to principal applicants and roughly 2,800 to eligible relatives, a category that currently includes spouses and unmarried children under age 21. That exceeds the number of visas issued in all years combined since the program was established in 2009. Still, the cases of more than 5,600 interpreters have yet to be adjudicated.

“The State Department and the other U.S. government departments and agencies involved in the Special Immigrant Visa process have the highest respect for the men and women who take enormous risks in helping our military and civilian personnel,” Harf wrote. “We are committed to helping those who — at great personal risk — have helped us.”

That sentiment is at odds with what many Afghans have experienced, according to interpreters and their advocates. Many who have been rejected or have given up on waiting for responses have spent their life savings on smugglers who offer to get them to Europe or Australia by boat — journeys that sometimes have ended fatally.

Some who have recently prevailed have done so after dogged lobbying by U.S. veterans. Adrian Kinsella, a Marine captain, started writing to members of Congress last year after his former interpreter, Mohammad, had been waiting for news on his visa petition for more than three years. Mohammad’s father had been killed by the Taliban and his 3-year-old brother had been kidnapped.

“I assumed it would be a slam-dunk application,” said Kinsella, 28, a law student at the University of California at Berkeley who remains on active duty but noted he was not speaking in an official capacity.

As he started attempting to prod the bureaucracy, Kinsella said he was dumbfounded by the byzantine process. It was impossible to get a person on the phone at any of the agencies. E-mails seeking updates were answered by automated messages that included no new information and requested that the applicant wait six months before inquiring again.

“I am a college-educated military officer, familiar with all kinds of bureaucracy,” he wrote last year to a senator, pleading for help. “Still, I have found the paperwork and frustration involved in this process to often rise to Kafkaesque levels.”

After several lawmakers took on Mohammad’s case, his visa was approved this year. Two weeks after he arrived in late January, Mohammad, who became Kinsella’s roommate, had a job and a car.

Mohammad said he has found life in the United States liberating but worries about his relatives and colleagues who are still waiting.

“There are no more jobs for them on the bases,” he said, noting that the U.S. military footprint is quickly shrinking around the country. “For the people who are still waiting, it is very difficult.”