A must-pass government funding package will expand gun rights for an unlikely group: veterans deemed mentally incompetent to manage their own affairs.

The rider, buried in the multipart “minibus” spending package, was enough to draw the opposition of Sen. Chris Murphy (D-Conn.), who has been a leading voice for gun reform since the mass shooting at Sandy Hook Elementary School in Newtown in 2012.

Though the rider was primarily backed by Republicans, six House Democrats voted in favor of it, according to Roll Call: Henry Cuellar and Vicente Gonzalez (Texas), Jared Golden (Maine), Mary Peltola (Alaska), Marie Gluesenkamp Perez (Wash.) and Gabe Vasquez (N.M.). Jon Tester (D-Mt.) favored the measure in the Senate.

The provision “will be a death sentence for many,” Murphy wrote Wednesday in a widely circulated series of tweets. “It’s unacceptable this provision was pushed by Republicans. Democrats shouldn’t have acquiesced.”

House Speaker Mike Johnson (R-La.) trumpeted the rider as a victory that “prevents the Department of Veterans Affairs from attacking Second Amendment rights.”

For decades, federal law has required the Veterans Affairs Administration to flag the beneficiaries it judges as “mentally incompetent” to the FBI, in order add them to the National Instant Criminal Background Check System (NICS), which blocks their future purchases of firearms.

The VA classifies beneficiaries as mentally defective in cases where the person cannot manage their affairs on their own, requiring a third party to take charge of their finances. The agency bases those decisions on medical evidence and court declarations, and offers processes for beneficiaries to contest the determination, as well as the NICS referral.

The change would block the VA from sending those referrals to the NICS database. Instead, the legislation would require a judge to sign off on those referrals in the future.

“I’m really disappointed that for the first time in 20 years, a new gun rider is being added to the appropriations bill,” Murphy told HuffPost. “This has the potential to get a lot of very seriously mentally ill veterans killed. It feels like we should be very careful, not cavalier, about schizophrenic veterans getting access to guns.”

Fiduciaries manage the financial affairs of some 67,000 veterans. A 2014 study found that VA health services treated some 120,000 veterans for schizophrenia and related disorders.

Mental disorders and incompetence are grounds for barring firearm possession under federal law. The VA refers more cases of mental defectiveness to the FBI than any other federal agency by far, accounting for 98% of federal referrals, according to a report published last year by the Congressional Research Service.

Veterans generally face an increased risk of suicide, according to data tracked by the Veterans Affairs Administration, and that risk appears to be growing. Nearly 6,400 veterans died by suicide in 2021, the most recent year for which the VA has released data. That figure marks an 11.6% increase from the year before. Suicide is the second-leading cause of death for veterans under 45.

Mental health disorders are a key risk factor for suicide among veterans, according to the VA. The report cited the increase in firearm availability following the nationwide gun-buying spree amid the pandemic as a possible factor in the rising risk of veteran suicides.

Republicans have pushed to limit the VA’s ability to refer cases of mental incompetence to the FBI, contending that an inability to manage financial affairs isn’t the same thing as having a life-threatening mental disorder.

The VA has opposed the Republican-led push to walk back the requirement to refer cases of mental incompetence to the FBI.

“Scientific research shows that mental health is one clear risk factor for suicide, and use of a firearm in a suicide attempt significantly reduces the chance of survival,” VA Deputy Under Secretary Ron Burke told the House Committee on Veterans Affairs last year.

Firearms account for nearly three-quarters of veteran deaths by suicide, compared to about half of suicides among non-veterans.

Igor Bobic contributed reporting.

If you or someone you know needs help, dial 988 or call 1-800-273-8255 for the National Suicide Prevention Lifeline. You can also get support via text by visiting suicidepreventionlifeline.org/chat. Outside of the U.S., please visit the International Association for Suicide Prevention for a database of resources.