The NRA-backed legislation rolls back a regulation put in place by President Barack Obama that adds a step to the gun background check process, requiring the Social Security Administration to check to see if the purchaser is receiving benefits after being deemed unable to hold a job and care for themselves due to mental impairment.
The 57 to 43 vote to revoke the regulation now sends the measure to President Donald Trump, who is expected to sign it.
After the Sandy Hook shooting tragedy which killed 20 children and six adults in 2012, President Barack Obama introduced a measure that required the Social Security Administration to report information on people with mental illness to the Federal Bureau of Investigation.More news: Cars Burn in Disneyland Parking Fire
Republican Sen. Chuck Grassley of Iowa has decried the rule.
"The regulation is flawed beyond any kind of fix", said Sen. The measure now goes to the White House for the president's signature. "Nothing. Instead, Republicans are trying to weaken the federal background check system used to keep guns out of the hands of unsafe people".
House Republicans passed a companion bill two weeks ago.More news: Humana, Aetna kill merger deal
Democrats said the rule was carefully tailored so that only people who were so incapacitated that they had someone receive their payments for them would be considered.
By voice vote, the Senate agreed on a motion to proceed to the resolution, potentially setting up a vote for final passage later Tuesday. A partner resolution has already passed the lower chamber along party lines 229-178. The VA submitted the names of veterans to the background check system when it was determined they could not manage their own financial affairs.
The NRA and the American Civil Liberties Union also opposed Obama's rule - the NRA for its restrictions on the Second Amendment, the ACLU for the possibility it would stereotype the mentally ill as violent.More news: Nintendo Switch trailer shows multiplayer fun
"Here, the rule automatically conflates one disability-related characteristic, that is, difficulty managing money, with the inability to safely possess a firearm", the organization said.