WASHINGTON -- The former U.S. congresswoman who was shot in the head in a 2011 mass shooting made a dramatic appeal to Congress on Wednesday for tougher gun control legislation, saying, "too many children are dying."

"Speaking is difficult. But I need to say something important," surprise witness Gabrielle Giffords said carefully. It was Congress' first gun control hearing since the fatal shooting of 20 young students in Connecticut in December pushed the long-sensitive issue to the top of President Barack Obama's agenda for his second term.

"Be bold, be courageous, Americans are counting on you," Giffords said.

The nation's most powerful gun lobby, the National Rifle Association, also testified before the Senate Judiciary Committee, whose divided members reflect the wider debate that gun limits will face on a path through Congress that promises to be difficult. An NRA official predicted that gun control measures will fail.

Obama this month proposed a package that includes banning military-style assault weapons, requiring background checks on all firearms purchases and limiting ammunition magazines to 10 rounds.

The U.S. has the world's highest rate of gun ownership, and gun sales have jumped since the Connecticut shooting as some fear that the government will take their guns away. The Constitution guarantees the right to bear arms, but some argue that the country's founding fathers more than two centuries ago couldn't have foreseen the speed and power of today's weapons.

Giffords and her husband, Mark Kelly, who are both gun owners, have formed a political action committee called Americans for Responsible Solutions to back lawmakers who support tighter gun restrictions and counter the influence of the NRA, which is known to punish lawmakers who stray from its point of view.

Kelly described to the panel Wednesday how Giffords' shooter fired 33 bullets in 15 seconds and was stopped when he paused to reload. The handgun would not have been illegal under a federal assault weapons ban that lapsed more than seven years ago, but the magazine that held more than 30 bullets would have been prohibited.

"We are simply two reasonable Americans who have said 'Enough,"' Kelly said. He added that the nation is "not taking responsibility for the gun rights our founding fathers have conferred on us."

The NRA has led past efforts to block stricter gun regulations, and it has promised to do it now.

NRA executive vice-president Wayne LaPierre said gun control measures had failed in the past "and will fail again in the future." He instead expressed support for better enforcement of existing laws, stronger school security and better government's ability to keep guns from mentally unstable people.

"Law-abiding gun owners will not accept blame for the acts of deranged criminals," LaPierre said.

LaPierre also conceded that in a reversal, the NRA no longer supports universal background checks for gun owners. He said the current system is a failure because the administration doesn't prosecute potential violators aggressively.

LaPierre's statement had a milder tone than recent NRA remarks, including a television ad that called Obama an "elitist hypocrite" for voicing doubts about the NRA proposal of armed guards in every school in the country while his own children are protected that way at their school. While Obama's children have Secret Service protection, officials at their school have said its own guards don't carry guns.

Even if gun control proposals make their way through a Congress that is already busy with immense fiscal issues and immigration, some law enforcement authorities at the local level have already threatened not to enforce them in sympathy for gun owners.

The chairman of the panel, Democratic Sen. Patrick Leahy, said closing loopholes in the background check system for gun purchasers won't threaten firearms owners' Second Amendment rights to own a gun and is a matter of common sense. Leahy said it's time to stop sloganeering and partisan recriminations on the subject.

"The Second Amendment is secure and will remain secure and protected," Leahy said.

By law, anyone buying a gun from a licensed dealer must have a background check, with convicted criminals and people with mental problems barred from purchases. Gun buyers at gun shows and online don't need the check.

Senate Majority Leader Harry Reid indicated that whatever the committee produced wouldn't necessarily be the final product, saying the package would be debated by the full Senate and senators would be allowed to propose "whatever amendments they want that deal with this issue."

It remains unclear whether those advocating limits on gun availability will be able to overcome resistance by lawmakers from states where gun ownership abounds. Question marks include not just many Republicans but also Democratic senators facing re-election in Republican-leaning states in 2014.

Democratic Sen. Dianne Feinstein, a Judiciary Committee member, has already introduced her own legislation banning assault weapons and magazines of more than 10 rounds of ammunition.