The Senate Armed Services Committee has authorized 4,000 new visas for Afghan interpreters who have risked their lives to serve the US government, a substantial increase that could help deal with a backlog of applications to a program that US officials say is a critical tool in the war in Afghanistan.

The 4,000 new visas are contained within the Senate’s version of the 2018 National Defense Authorization Act, a must-pass bill which the committee finalized this week.

The program is designed to help Afghan interpreters and translators who have served the US government and faced serious threats — often originating from the Taliban — find safe haven in the US. Family members who have received threats can also qualify for the program.

The Armed Services Committee authorized just 1,500 visas in the last defense bill as a result of opposition from some key Republicans — who raised concerns about the cost and increasing immigration to the US — compared to 3,000 in the 2016 version of the bill, and 4,000 the year prior.

The recent failures by Congress to authorize additional visas for the program forced the State Department to halt new interviews for the program in March of this year. The department said in April that it had 1,437 visas left and a backlog of more than 13,000 applications, not including the families of those who had applied.

In an emergency measure, senators included 2,500 more visas for the program in a must-pass government funding bill in early May.

New Hampshire Sen. Jeanne Shaheen, a Democrat on the Armed Services Committee who offered the amendment that led to the inclusion of the 4,000 additional visas in the new NDAA, said in a statement on Wednesday that she was “very pleased” with the result.

“Make no mistake, the Special Immigrant Visa program saves the lives of Afghan interpreters and support staff who stood shoulder-to-shoulder with Americans in the field, putting themselves and their families at risk to help our soldiers and diplomats accomplish their mission and return home safely,” Shaheen said. “I hope that the agreement reached today signals that Congress can begin authorizing additional visas without controversy and foot-dragging.”

The program has faced opposition in the past from some Republicans on the Senate Judiciary Committee, which has partial jurisdiction over the visa program. Judiciary Committee Chair Chuck Grassley previously argued that the State Department should use up all the visas it has before Congress authorizes more.

Grassley’s office did not immediately respond to questions about whether he had changed his mind.

The NDAA will now go to the full Senate for a vote some time later this year. The House is working on its own version of the bill and the two chambers will need to reconcile any policy differences before it can become law. The current NDAA expires at the end of September.