A top U.S. Democratic lawmaker on Thursday proposed a ban on assault weapons, like those used in a Connecticut school massacre last month, and called on the public to help overcome opposition by the powerful gun lobby.
"Getting this bill signed into law is an uphill battle, I recognize that, but it is a battle worth having," Senator Dianne Feinstein - flanked by fellow lawmakers, mayors and law enforcement officers - told a packed news conference.
Feinstein's bill would ban semi-automatic assault weapons as well as high-capacity ammunition clips like those used by a gunman in the December shooting spree at an elementary school in Newtown, Connecticut, that killed 20 children and six adults.
The massacre galvanized public support for tougher gun laws, but also rallied pro-gun rights groups like the National Rifle Association to oppose such action.
"If anyone asked today, 'Can you win this?' The answer is we don't know," said Feinstein, who asked Americans to pressure Congress.
"There is one great hope out there and that is you. Because you are stronger than the gun lobby. You are stronger than the gun manufacturers, but only if you stand up," said Feinstein, a senator from California.
Gun control advocates figure they need to move quickly before lawmakers become distracted with other matters. Feinstein's legislation mirrors some of the proposals that President Barack Obama offered last week as he vowed to make gun control a top priority in his second term.
Banning assault weapons is seen as the part of Obama's package least likely to win approval in Congress. A previous ban expired in 2004 after 10 years. Other portions include expanded background checks for gun purchasers and improvements in mental health treatment.
With 310 million guns in civilian hands and 11,000 homicides with firearms last year, the United States is one of the world's most heavily armed and violent countries.
Feinstein's bill would ban semi-automatic rifles that can accept a detachable magazine clip. It would also prohibit clips with more than 10 rounds.
In an effort to ease opposition, the bill would exempt any weapon already legally owned as well as 2,258 specific models and makes of hunting and sporting rifles and shotguns.
"Senator Feinstein has been trying to ban guns from law-abiding citizens for decades. It's disappointing but not surprising that she is once again focused on curtailing the Constitution instead of prosecuting criminals or fixing our broken mental health system," the NRA said in a statement.