Congress has voted to renew a ban on plastic firearms that could evade detection machines after an effort to pass tougher restrictions was blocked by Republicans.
The Senate approved a 10-year extension of the prohibition against guns that can slip past metal detectors and X-ray machines by voice vote Monday night, narrowly beating a midnight deadline.
The House voted last week for an identical, decade-long renewal of the ban, and the measure now goes to President Obama for his signature.
However, GOP senators rejected an effort led by Sen. Chuck Schumer to make the ban tougher by requiring such weapons contain undetachable metal parts. Some plastic guns meet the letter of the current law with a metal piece that can be removed, meaning they could potentially be slipped past security screeners at schools, airports and elsewhere.
In a press conference after the vote, Schumer said he is happy the renewal passed but believes it is "bad news" that the security screener loophole was not addressed. He said he hopes to work with his colleagues to get to a compromise to address the security issue, saying he is worried it could be a weak spot terrorists could exploit.
The National Rifle Association expressed no opposition to renewing the law, but said it would fight any expanded requirements, including Schumer's, "that would infringe on our Second Amendment rights" to bear arms.
Underscoring the issue's political sensitivity, both of Monday's votes were by voice only, meaning no individual senator's vote was recorded. For a handful of Democratic senators seeking re-election next year in GOP-leaning states, the day's votes could have been difficult.
The rejection of stricter curbs highlighted the repeated setbacks for gun-control advocates in Congress since last Dec. 14. On that day, a gunman fatally shot 20 first-graders and six staff members at Sandy Hook Elementary School before killing himself.
Despite that -- and other recent mass shootings, including at the Washington Navy Yard just blocks from the Capitol -- supporters of expanded gun control are nearing the end of a year in which they have been unable to push any new firearms restrictions through Congress.
"We're several decades behind the NRA," said Sen. Chris Murphy, D-Conn. "This is a long game, and it's going to take us some time to build up the resources necessary to compete."
Congressional Republicans have resisted tightening the restrictions against undetectable guns, but those lawmakers -- as well as the NRA -- have not opposed renewing the current prohibition. The House approved a 10-year extension last week.
Plastic guns were in their infancy when President Ronald Reagan and Congress first enacted the ban against undetectable firearms, and when it was renewed in 1998 and 2003. But such weapons have become a growing threat and can now be produced by 3-D printers, which are becoming better and more affordable.
Sen. Charles Grassley of Iowa, top Republican on the Senate Judiciary Committee, says that with the law's expiration at hand, Congress should extend it for a decade and study Schumer's more restrictive plan later.
Supporters of tightening the rules say the 10-year renewal helps the gun lobby because it reduces Democrats' ability to revisit the issue.
The Associated Press contributed to this report