WASHINGTON -- President Barack Obama urged a reluctant Congress Wednesday to require background checks for all gun sales and ban both military-style assault weapons and high-capacity ammunition magazines in an emotion-laden plea to curb gun violence in America.
The president's plan, coming one month after the school massacre in Connecticut, marks the most comprehensive effort to tighten gun laws in nearly two decades. But his proposals, most of which are opposed by the National Rifle Association, face a doubtful future in a divided Congress where Republicans control the House.
Seeking to circumvent at least some opposition, Obama signed 23 executive actions, including orders to make more federal data available for background checks and end a freeze on government research on gun violence. But he acknowledged that the steps he took on his own would have less impact than the broad measures requiring approval from Capitol Hill.
"To make a real and lasting difference, Congress, too, must act," Obama said, speaking at a White House ceremony with schoolchildren and their parents. "And Congress must act soon."
The president's announcements capped a swift and wide-ranging effort, led by Vice President Joe Biden, to respond to the deaths of 20 children and six adults at Sandy Hook Elementary School in Newtown, Conn.
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"I will put everything I've got into this, and so will Joe," the president said. "But I tell you, the only way we can change is if the American people demand it."
Key congressional leaders were tepid in their response to the White House proposals.
Senate Majority Leader Harry Reid (D-Nev.) said he was committed to ensuring that the Senate will consider gun violence legislation "early this year." But he did not endorse any of Obama's specific proposals.
The president vowed to use "whatever weight this office holds" to fight for his recommendations.
"This is our first task as a society, keeping our children safe," Obama said. "This is how we will be judged."
Obama is likely to travel around the country in the coming weeks to rally public support and could engage his still-active presidential campaign operation in the effort. But he will have to overcome a well-financed counter-effort by the NRA.
The president, speaking in front of an audience that included families of some of those killed in Newtown, said 900 Americans had lost their lives to gun violence in the four weeks since the school shootings.
"We can't put this off any longer," Obama declared. "Every day we wait, the number will keep growing."
Many Democrats say an assault weapons ban faces the toughest road in Congress. Obama wants lawmakers to reinstate the expired 1994 ban on the high-grade weapons. The president is also likely to face opposition to his call for Congress to limit ammunition magazines to 10 rounds.
But Democrats are hopeful they can build consensus around the president's call for universal background checks.
The Brady Campaign to Prevent Gun Violence says 40 percent of gun sales are conducted with no criminal background checks, such as in some instances at gun shows or by private sellers over the Internet or through classified ads.
NEED CONGRESSIONAL APPROVAL
Require criminal background checks on prospective buyers in all gun sales. Federally licensed firearms dealers now are required to run checks on gun buyers, but studies estimate that nearly 40 percent of sales are made by private sellers who are exempt from the requirement.
Renew and strengthen the federal ban on sales of military-style assault weapons that was in effect from 1994 to 2004.
Reinstate a ban on magazines holding more than 10 rounds.
Ban the possession of armor-piercing ammunition and its transfer to anyone other than the military and law enforcement.
Increase punishments for gun trafficking, particularly by unlicensed dealers or straw buyers who purchase arms for criminals.
Give $150 million to school districts and law enforcement agencies to hire school resource officers -- specially trained police officers who work in schools -- and counselors.
Reach 750,000 young people through programs to identify mental illness early and refer them to treatment.
EXECUTIVE ACTION BY OBAMA
Make it easier for states to make data, notably about those with mental health issues, available to the background check system.
Direct the Centers for Disease Control and scientific agencies to conduct research into causes and prevention of gun violence.
Launch a national responsible gun ownership campaign.
Require federal law enforcement to trace guns recovered in criminal investigations.