WASHINGTON (AP) -- President Barack Obama on Wednesday launched the most sweeping effort to curb U.S. gun violence in nearly two decades, announcing a $500 million package that sets up a fight with Congress over bans on military-style assault weapons and high-capacity ammunition magazines just a month after a shooting in Connecticut killed 20 school children.
Obama also signed 23 executive actions -- which require no congressional approval -- requiring federal agencies to make more data available for background checks, appointing a full-time director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, and directing the Centers for Disease Control to research gun violence.
But the president, speaking at the White House, acknowledged the most effective actions must be taken by lawmakers.
"To make a real and lasting difference, Congress must act," Obama said. "And Congress must act soon."
Obama was flanked by children who wrote him letters about gun violence in the weeks following the Connecticut shooting. Families of the children killed in the shooting, as well as survivors, were also in the audience.
The announcement promises to set up a bitter fight with a powerful pro-gun lobby that has long warned supporters that Obama wanted to take away their guns.
The U.S. has the highest rate of gun ownership of any country in the world, and pro-gun groups see any move on gun restrictions as an offense against the right guaranteed by the Second Amendment of the U.S. Constitution. Critics counter that the country's founding fathers never could have foreseen assault weapons more than two centuries ago, when guns were intended for the common, not individual, defense, guns were often stored in community areas and rifles fired one shot at a time.
"This is the land of the free and the home of the brave and always will be," Obama said, acknowledging the right to bear arms. "But we've also long realized ... that with rights come responsibilities."
Emotions have been high since the Connecticut shooting, which Obama has called the worst day of his presidency. He largely ignored the issue of gun violence during his first term but appears willing to stake his second term on it now. He'll have to contend with looming fiscal issues that have threatened to push whatever he proposes aside, at least for a while.
Gun control advocates also worry that opposition from the powerful National Rifle Association and its allies in Congress will be too great to overcome. The NRA released an online video Tuesday that called Obama an "elitist hypocrite" for having armed Secret Service agents protect his daughters at school while not committing to installing armed guards in all schools. The NRA insists that the best way to prevent more mass shootings is to give more "good guys" guns.
The White House called the NRA video "repugnant and cowardly."
The public appears receptive to stronger federal action on guns, with majorities of Americans favoring a nationwide ban on military-style rapid-fire weapons, according to a new Associated Press-GfK poll. The poll also shows 84 percent of adults would like to see the establishment of a federal standard for background checks for people buying guns at gun shows.
Three-quarters of Americans said they reacted to the Connecticut shooting with deep anger, while 54 percent said they felt deeply ashamed it could happen in the United States.
The new poll also shows 51 percent said they believed laws limiting gun ownership infringe on the public's constitutional right to possess and carry firearms.
White House officials, seeking to avoid setting the president up for failure, have emphasized that no single measure -- even an assault weapons ban -- would solve the scourge of gun violence. But without such a ban, or other sweeping Congress-approved measures, it's unclear whether executive actions alone can make any noticeable difference.
The president called for banning assault weapons and limiting ammunition magazines to 10 rounds or fewer, and he proposed a federal statute to stop purchases of guns by buyers who are acting for others.
The president also called for a focus on universal background checks. Some 40 percent of gun sales take place without background checks, including those by private sellers at gun shows or over the Internet, according to the Brady Campaign to Prevent Gun Violence.
The president's framework is based on recommendations from Vice President Joe Biden, who led a wide-ranging task force on gun violence. Beyond the gun control measures, Biden also gave Obama suggestions for improving mental health care and addressing violent images in video games, movies and television.
States and cities have been moving against gun violence as well.
New York Gov. Andrew Cuomo on Tuesday signed into law the toughest gun control law in the U.S., and the first since the Connecticut school shootings. The law includes a tougher assault-weapons ban and provisions to try to keep guns out of the hands of mentally ill people who make threats.
The NRA criticized the bill, saying in a statement, "These gun control schemes have failed in the past and will have no impact on public safety and crime."
In Washington, it's unclear how much political capital Obama will use in pressing for congressional action.
The White House and Congress will soon be consumed by three looming fiscal deadlines, each of which is expected to be contentious. And the president has also pledged to tackle comprehensive immigration reform early this year, another effort that will require Republicans' support.
The top Republican in the Senate, Mitch McConnell, has warned the White House that it will be at least three months before the chamber considers gun legislation. And Senate Majority Leader Harry Reid, a Democrat, has said immigration, not gun control, is at the top of his priority list after the fiscal fights.
Congress, in any case, can move slowly. The chairman of the Senate Judiciary Committee said Wednesday he'll begin hearings in two weeks on gun safety proposals.
Democratic Sen. Patrick Leahy, a gun owner, said he envisions a series of hearings examining violence in popular media and how to keep guns safe, among other topics.
Leahy's plan could take more time than Obama has urged.
Associated Press writers Julie Pace, Erica Werner, Ken Ritter, Josh Lederman Michael Gormley and Michael Virtanen contributed to this report.