U.S. President Barack Obama is urging a reluctant Congress 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, though he acknowledged he's in for an uphill battle.

The president's sweeping, $500 million 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 powerful National Rifle Association and its allies in Washington, face a doubtful future in a divided Congress where Republicans control the House of Representaives.

What are executive orders?

Executive orders are directives issued by the president that carry the weight of a federal law. A somewhat nebulous concept, these orders have no specific basis in the U.S. Constitution. They are used to direct and manage the federal government.

They have typically been used to alter existing laws instead of creating new ones and Congress can override an executive order by passing legislation that opposes it. The Supreme Court can also overturn executive orders.

However, some executive orders have lead to widespread changes to the country including a directive issued by President Franklin D. Roosevelt to relocate and imprison citizens of Japanese ancestry during the Second World War.

Presidents usually issue a number of executive orders each year, ranging from just a handful to several hundred. Critics have often decried the use of the directives as an abuse of power.

Seeking to circumvent at least some opposition, Obama signed 23 executive actions on Wednesday, 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 Congress.

"To make a real and lasting difference, Congress, too, must act," Obama said, speaking at a White House ceremony with school children 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, Connecticut. But Obama's gun control proposals set him up for a tough political fight with Congress as he starts his second term, when he'll need Republican support to meet three looming fiscal deadlines and pass comprehensive immigration reform.

Obama likely to face opposition from Congress, NRA

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, and strengthen the measure to prevent manufacturers from circumventing the prohibition by making cosmetic changes to banned guns.

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 per cent 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.

Gun shop owner Brooke Misantone (right) shows his last two AR-15 style rifles to a group of customers at the Bullet Hole gun shop in Sarasota, Fla. on Wednesday. Gun shop owner Brooke Misantone (right) shows his last two AR-15 style rifles to a group of customers at the Bullet Hole gun shop in Sarasota, Fla. on Wednesday. (Brian Blanco/Reuters)

NRA is opposed to all three measures. In a statement Wednesday, the gun lobby said, "Only honest, law-abiding gun owners will be affected" by Obama's efforts and the nation's children "will remain vulnerable to the inevitability of more tragedy."

Key congressional leaders were tepid in their response to the White House proposals.

Republican House John Boehner's office signalled no urgency to act, with spokesman Michael Steel saying only that "House committees of jurisdiction will review these recommendations. And if the Senate passes a bill, we will also take a look at that."

Democratic Senate Majority Leader Harry Reid 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.

Obama's long list of executive orders includes the following:

  • Ordering tougher penalties for people who lie on background checks and requiring federal agencies to make relevant data available to the federal background check system.
  • Ending limits that make it more difficult for the government to research gun violence, such as gathering data on guns that fall into criminal hands.
  • Requiring federal law enforcement to trace guns recovered in criminal investigations.
  • Giving schools flexibility to use federal grant money to improve school safety, such as by hiring school resource officers.
  • Giving communities grants to institute programs to keep guns away from people who shouldn't have them.

The president vowed to use "whatever weight this office holds" to fight for his recommendations. He's 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'll have to overcome a well-financed counter-effort by the NRA.

"This will be difficult," Obama acknowledged. "There will be pundits and politicians and special interest lobbyists publicly warning of a tyrannical, all-out assault on liberty — not because that's true, but because they want to gin up fear or higher ratings or revenue for themselves."

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."

On the eve of Obama's announcement, the NRA released an online video accusing him of being an "elitist hypocrite" for sending his daughters to school with armed Secret Service agents while opposing having guards with guns at all U.S. schools.

White House spokesman Jay Carney called the video "repugnant and cowardly."

The president's proposals did include a $150 million request to Congress that would allow schools to hire 1,000 new police officers, counsellors and psychologists. The White House plan also includes legislative and executive action to increase mental health services, including boosting funding for training aimed at getting young people into treatment more quickly.

Proposal for more research into gun violence

A lopsided 84 per cent of Americans back broader background checks, according to a new Associated Press-GfK poll. Nearly six in 10 Americans want stricter gun laws, the same poll showed, with majorities favouring a nationwide ban on military-style weapons and limits on gun violence depicted in video games, movies and TV shows.

The NRA and pro-gun lawmakers have long suggested that violent images in video games and entertainment are more to blame for mass shootings than the availability of guns. But Obama's proposals do little to address that concern, other than calling on the Centers for Disease Control and Prevention to research links between violent images and gun attacks.

Government scientists have been prohibited from researching the causes and prevention of gun violence since 1996, when a budget amendment was passed that barred researchers from spending taxpayer money on such studies.

The administration is calling on Congress to provide $10 million for expanded research.

Obama also wants lawmakers to ban armour-piercing ammunition, except for use by the military and law enforcement. And he's asking them to create stiffer penalties for gun trafficking, to provide $14 million to help train police officers and others to respond to shootings, and to approve his nominee to run the Bureau of Alcohol, Tobacco, Firearms and Explosives.