Democrats agreed the government must not stigmatize those with disabilities but said the rule affects a small group with severe, long-term mental disorders preventing them from doing any work.
The Senate voted Wednesday morning to eliminate a regulation aimed to stop people with mental disorders from buying firearms.
The reversal of the law passed the House last week, and is expected to be approved by President Donald Trump.
The rule on the verge of rollback would have required the Social Security Administration to report the records of some mentally ill beneficiaries to the FBI's National Instant Criminal Background Check System. Supporters argued the rule kept some with serious mental health issues from buying guns.
While it's no great shock that the National Rifle Association (NRA) supports the rule's repeal, a more telling sign may be that the move has also earned the support of the American Civil Liberties Union (ACLU).
The regulation was crafted as part of President Barack Obama's efforts to strengthen the federal background check system in the wake of the 2012 massacre of 20 young students and six staff at Sandy Hook Elementary School in Newtown, Connecticut.
Critics of the rule said it denied people not dangerously mentally ill, such as those with eating or sleep disorders, from owning firearms.
The House voted against the rule on February 3.
"If you can't manage your own financial affairs, how can we expect that you're going to be a responsible steward of a risky, lethal firearm", Murphy said.
The vote has been criticized by gun control advocates who believe it's important to keep deadly weapons out of the hands of people deemed too severely mentally ill to manage their own disability benefits.
And according to Oregon Democrat, Senator Ron Wyden, the issue is not about constitutional rights, it's about background checks: "As the courts continue to interpret the language of the Second Amendment, one matter has been made clear".
"The Second Amendment, as a fundamental right, requires the government to carry the burden to show a person has risky mental illness, ".