WASHINGTON D.C. (NEXSTAR) – More than 6,000 orange envelopes mailed by Vietnam veterans across the country have arrived at the White House, the VA and now a Senate Veterans’ Affairs Committee hearing.

“Most of you have probably received letters in the bright orange envelopes like these,” said U.S. Sen. John Boozman, (R-AR). “Constituents coming forward, talking about problems they’re having and then translating that to legislation. Bill Rhodes did a great job of doing that.”

Boozman has been working with Rhodes, a Vietnam veteran in his home state who is behind the letter campaign, on legislation that would allow more veterans who served in Thailand to be eligible for Agent Orange benefits.

“It is so restrictive in Thailand. It’s just to the perimeter, and you have to be essentially a military policeman,” said Boozman.

Veterans like Rhodes are suffering from diseases that research indicates were likely caused by exposure to the toxic herbicide, but right now, they can’t apply for benefits.

“It makes no sense that if you were in the interior of the base or posted patrolling for some other reason that you wouldn’t be able to qualify,” said Boozman.

Arkansas Congressman Bruce Westerman has also been working on the legislation in the House.

“It bothers me that here we are this many years later, and we’ve got veterans still trying to get benefits that they were promised long ago,” said Westerman.

At Wednesday’s hearing, the Veterans Affair’s chief consultant on the matter says the VA is currently evaluating a list of more locations from the U.S. Department of Defense that could be linked to Agent Orange exposure.

“We are looking at it right now. It is with my office and with VBA [Veterans Benefits Administration]. We hope to post that soon,” said Dr. Patricia Hastings, VA Post-Deployment Health Chief Consultant.

But Hastings wouldn’t make any promises about helping veterans like Rhodes.

Congress recently passed a similar bill, the Blue Water Navy Vietnam Veterans Act, that extends Agent Orange benefits to veterans who were serving on ships off of the coast of Vietnam.

Hastings said the VA is trying to hire more people to start processing claims next year.