The Republican-led Senate has voted to block an Obama-era regulation that would prevent an estimated 75,000 people with mental disorders from being able to purchase a firearm.
The 57 to 43 vote to revoke the regulation now sends the measure to President Donald Trump, who is expected to sign it.
The Obama administration rule strengthened the federal background check system by requiring the Social Security Administration to include the names of beneficiaries with mental impairments who also have a third party to manage their benefits.
But critics say the rule was too broad and unfairly stigmatised the disabled.
With a Republican ally in the White House, the GOP has moved aggressively to rescind several late Obama administration regulations.