US President Barack Obama, criticized by some for his inaction on gun violence in the past four years, launched an aggressive battle on Wednesday for a package of measures on firearms control.

With four children from Sandy Hook Elementary School in Newtown, Connecticut, sitting next to his podium, Obama outlined his 23 executive orders and more than a dozen proposals that he hoped to pass in Congress. They include measures to ban assault weapons, impose a 10-round limit on ammunition magazines, and expand background checks for gun buyers.

The deadly shooting at the school a month ago took the lives of 20 children and six adults.

Obama vowed that he and US Vice-President Joe Biden will put everything they have into the fight. "Because while there is no law or set of laws that can prevent every senseless act of violence completely, no piece of legislation that will prevent every tragedy, every act of evil, if there's even one thing we can do to reduce this violence, if there's even one life that can be saved, then we've got an obligation to try," Obama said.

"Weapons designed for the theater of war have no place in a movie theater. A majority of Americans agree with us on this," he said, referring to the theater shooting in Aurora, Colorado, in late July in which 12 were killed and 58 others injured.

In an effort to rally Republicans, Obama praised former US president Ronald Reagan for writing to Congress in 1994 to urge its members to listen to the public and to the law enforcement community and support a ban on the further manufacture of military-style assault weapons.

The assault-weapon ban was signed into law by then-US president Bill Clinton in 1994, but it expired in 2004. Many Democratic lawmakers have not pushed aggressively for its renewal, fearing they would lose their re-election bids.

Obama hoped that the public would put pressure on lawmakers. "Ask them what's more important: doing whatever it takes to get an ‘A' grade from the gun lobby that funds their campaigns, or giving parents some little peace of mind when they drop their children off for first grade," he said.

A Pew Center poll released this week shows that Americans are sharply divided on the issue. Just over half ― 51 percent ― favored controlling gun ownership, while 45 percent put the priority on protecting the rights of Americans to own guns. There has been little change from the poll conducted right after the Newtown shooting in mid-December.

New York City Mayor Michael Bloomberg, one of the nation's strongest advocates for gun control, praised Obama for the measures on Wednesday. He and Boston Mayor Thomas Menino, who co-chair Mayors Against Illegal Guns, an organization of about 1,000 mayors across the US, had gathered dozens of members on Capitol Hill on Wednesday to lobby lawmakers to support gun control measures.

On Tuesday, New York state Governor Andrew Cuomo signed into law a package of gun-control measures. It expands a ban on assault weapons and reduces the permissible size of gun magazines to seven rounds, from the previous 10. However, opponents of gun control have launched counterattacks.

The National Rifle Association, the strongest gun-rights lobby in the US, issued a statement after Obama's speech, saying: "Attacking firearms and ignoring children is not a solution to the crisis we face as a nation. Only honest, law-abiding gun owners will be affected, and our children will remain vulnerable to the inevitability of more tragedy."

The NRA released a video online on Tuesday, pointing out Obama's opposition to deploy armed security in public schools and accusing him of hypocrisy.