US lawmakers have dropped an effort to include a ban on assault weapons in a broader gun control package, conceding the difficulties of passing such legislation through Congress.
The move by Senate Majority Leader Harry Reid on Tuesday does not kill the proposal outright, but separating it from three other measures being pushed by President Barack Obama's Democrats leaves it to wither in today's highly partisan Congress.
Reid said the ban, which included high-capacity magazines, proposed after last year's mass murder of school children in Newtown, Connecticut, did not have the votes to pass.
Democratic Senator Dianne Feinstein had tabled the ban which had support from many in her party, but not enough from fellow senators to pass.
"Right now her amendment, using the most optimistic numbers, has less than 40 votes," Reid said. "I have to get something on the floor so we can have votes on that issue."
Controversial bills need 60 votes to ensure that they are not derailed by a filibuster, a parliamentary manoeuvre to prevent them coming to a vote.
Democrats, who hold 55 Senate seats, had sought Republican support for four measures, including that background checks be required for all gun sales, which they hoped to cobble together into one bill. The other three have a chance of winning some modest Republican support and have somewhat better odds of getting through both houses of Congress.
The assault weapons ban, backed by the White House, passed out of committee last week on a strict party-line vote.
It still could be voted on separately, and while that would be expected to fail, Feinstein was standing firm about demanding Reid allow her such a vote.
"I'm not going to lay down and play dead," she said on CNN. "I think the American people have said in every single public poll that they support this kind of legislation."
Not allowing her a floor vote "would be a major betrayal of trust," she said, noting that Reid told her she would have an opportunity for one.
The ban's lukewarm support among Democrats was "the handwriting on the wall," Republican Senator James Inhofe said, adding he believed "zero" bills tightening gun laws would pass Congress this year.
The measure would have prohibited the manufacture, import and sale of 157 models of assault weapons, including that used on December 14 to kill 20 schoolchildren and six adults at Sandy Hook Elementary School.