Senate Majority Leader Harry Reid on Tuesday declared politically dead the effort to ban military-style assault weapons, a setback for President Barack Obama and gun-control advocates who are pushing the Senate to move quickly on bills to limit gun violence.

Reid is preparing to move ahead with debate on a series of gun-control proposals when the Senate returns from a two-week Easter recess in early April. Although he has vowed to hold votes on measures introduced after the Sandy Hook Elementary School massacre in Newtown, Connecticut, in December, Reid said Tuesday the proposed assault-weapons ban isn't holding up against Senate rules that require at least 60 votes to end debate and move to final passage.

The proposed ban, "using the most optimistic numbers, has less than 40 votes. That's not 60," Reid said.