As the Trump administration continues its fight against the legalization of marijuana, a somewhat surprising force is pushing back.

The American Legion and its 2 million military veteran members are launching campaigns to end restrictions on marijuana usage. The organization argues that laws against marijuana hurt former soldiers who often suffer from various physical ailments as a result from their service. Since they’re not allowed access to cannabis products, veterans are forced to use more powerful and addictive opioids. The Legion argues marijuana would be far more preferable.

“We were hearing these compelling stories from veterans about how cannabis has made their lives better,” American Legion spokesman Joseph Plenzler told the Los Angeles Times. “That they were able to use it to get off a whole cocktail of drugs prescribed by VA doctors, that it is helping with night terrors, or giving them relief from chronic pain.”

The impact of the veterans is already being seen in Washington D.C. Earlier this month, a Senate budget committee approved a measure that would allow VA doctors to prescribe medical marijuana to their patients in states where it is legal, with nine Republicans voting in favor of the measure. A member of a centrist think tank told the LA Times that “This is one marijuana issue a lot of Republicans are interested in.”

Another important aspect of the marijuana debate for veterans is suicide and accidental overdose. A 2015 report from the National Bureau of Economic Research found that states with legal medical marijuana saw 16 percent fewer opioid overdose deaths than states where it is illegal. Likewise, many veteran suicides have been attributed to opioid addiction. There are also ongoing federally-funded research projects trying to determine the impact marijuana can have on post-traumatic stress disorder (PTSD), a condition that many veterans suffer from.

While some congressional Republicans may be coming around to the idea, there isn’t any evidence that the arguments is resonating within the Trump administration, as Attorney General Jeff Sessions continues to argue that “marijuana has no accepted medical use under federal law.”

But perhaps if more traditionally conservative groups join the legalization fight, Republicans will be forced to evolve.