Democratic senators have unveiled their measure to reintroduce the assault weapons ban in the aftermath of the Newtown massacre that killed 27 people, including 20 children, last month. Sen. Dianne Feinstein of California and Sen. Chris Murphy of Connecticut announced the new legislation on Thursday.

Sen. Dianne Feinstein: “Weapons designed originally for the military to kill large numbers of people in close combat are replicated for civilian use. They fall into the hands, one way or another, of grievance killers, of gangs, of those who are mentally unstable or ill.”

Sen. Christopher Murphy: “Kids would be alive today in Newtown, Connecticut, if the law that we’re proposing today were in place on December 14th of last year. It’s as simple as that. Why do we know that? We know that because the data tells us, despite what the gun lobby will say, that the first assault weapons ban, even with its warts, worked.”

The measure would outlaw the manufacture and sale of 157 types of semi-automatic rifles and of magazine clips holding more than 10 rounds. The previous assault weapons ban expired in 2004 after 10 years in effect. The new measure is expected to meet stiff resistance from House Republicans and even some Senate Democrats in states with loose restrictions on firearms.