Senate Majority Leader Harry Reid of Nevada said the gun control legislation would not get the 60 votes it would need to pass on the Senate floor with the ban included, the Washington publication Politico reported.
Reid said Sen. Dianne Feinstein, D-Calif., who sponsored the ban language and marshaled it through the Judiciary Committee on a 10-8 vote last week, "worked so hard on this" since she found San Francisco Mayor George Moscone assassinated in his office in 1978, but it lacks wide enough support.
"I know that, but right now her amendment, using the most optimistic numbers, has less than 40 votes. That's not 60," Reid said. "I have to get something on the floor so we can have votes on that issue and the other issues."
He said he was aiming for a vote next month after the Senate returns from its Easter break.
Feinstein said she was "obviously ... disappointed," but said separate amendments providing for the assault weapons ban and outlawing large-capacity clips would get floor votes, The Washington Post reported.
"The enemies on this are very powerful, I've known that all my life," Feinstein said, referring to the National Rifle Association. "But I'm confident this bill would be constitutional."
Roll Call reported Feinstein said she "tried my best, but my best, I guess, wasn't good enough."