"Too many children are dying," the former Arizona congresswoman, speaking slowly, told the U.S. Senate judiciary committee in a surprise appearance as the hearing began.
"Speaking is difficult, but I need to say something important ... Be bold, be courageous. Americans are counting on you."
Giffords has become the unwitting poster child for gun violence ever since a would-be assassin shot her in the head two years ago, killing six others in his attempt.
She's stepped up her efforts to curb gun violence following the horrific mass shooting of 26 people, 20 of them first graders, in small-town Connecticut in December by a troubled 20-year-old man toting his mother's assault weapons.
In the wake of that dreadful shooting, U.S. President Barack Obama has called for a renewed ban on semi-automatic weapons and high-capacity magazines, as well as more extensive background checks on gun purchasers. Polls suggest the majority of Americans are now behind him.
That growing public support for gun control wasn't reflected Wednesday by the members of the judiciary committee, who are starkly divided on the issue.
Their divisions highlight the difficulties that will most certainly plague any legislative attempts to thwart gun violence in a country with an estimated 300 million guns in circulation.
Indeed, a ban on assault weapons isn't even expected to pass the Democratic-controlled Senate. The four-hour Senate hearing focused more on background checks than it did on a bill introduced by Sen. Dianne Feinstein that would outlaw assault rifles and high-capacity ammunition magazines.
Even Sen. Patrick Leahy, the Democratic chairman of the committee, failed to endorse Feinstein's bill as he kicked off the packed hearing.
Senate majority leader Harry Reid has also suggested he won't back the bill, saying it will fail to get votes from conservative Democratic senators — many of them facing tough re-election battles in 2014 in traditionally Republican states.
That's music to the ears of the National Rifle Association, the powerful lobby group that insists it merely advocates for the Second Amendment rights of average American citizens. In recent years, however, there's been increasing evidence that the NRA receives funding from gun manufacturers.
Executive vice-president Wayne LaPierre, a witness at the hearing, sparred with Sen. Dick Durbin, who took issue with the NRA's insistence that background checks are pointless because criminals won't submit to them.
LaPierre said the NRA even opposes background checks at gun shows — where none are currently required — arguing that more background checks would merely subject "law-abiding people" to more taxes, fees and hassles without catching "bad guys."
"Mr. LaPierre, that's the point," Durbin said. "The criminals won't get to purchase the guns because there'll be a background check. We'll stop them from the original purchase — you missed that point completely. I think it's basic."
LaPierre replied angrily: "Senator, I think you missed the point!" Leahy banged his gavel and called for order.
Giffords' husband, astronaut Mark Kelly, and the police chief for Baltimore County in Maryland were the only gun control advocates at the four-hour hearing; the three other witnesses were opposed to tougher gun control measures.
Both Kelly and James Johnson argued forcefully for universal background checks as well as an assault weapons ban.
Johnson also gently mocked LaPierre's argument that Americans need guns to "defend themselves from tyranny."
"What people all over the country fear today is that they are going to be abandoned by their country," LaPierre said. "If a tornado hits, if a hurricane hits, if a riot occurs, that they are going to be out there alone and the only way they are going protect themselves in the cold, in the dark, is with a firearm."
Durbin then asked Johnson to respond to LaPierre's statement.
"I find it to be scary, creepy, and simply just not based on logic," Johnson said. "Frankly, I can't relate to that kind of thinking."
Canada came up throughout the course of the hearings, when one gun rights advocate told the senators that Canadians repealed the national gun registry last year because it was such a "fiasco."
In fact, the government abolished the long-gun registry; assault weapons remain outlawed in Canada. The RCMP also privately expressed concerns to the government about the negative impact the repeal would have on its ability to trace long guns used in crimes.
Sen. Leahy, a Vermont lawmaker, told the hearing that gun violence does not plague Canada the way it does the United States.
"I live an hour's drive from Canada, and I don't see this same kind of problem there," he said.
Perhaps the most surreal moments of the hearing were provided by Gayle Trotter, a gun rights activist at the Independent Women's Forum.
Trotter, an attorney, insisted that women across the United States wanted assault rifles in order to protect their children, prompting some spectators at the hearing to burst into derisive laughter.
"Young women are speaking out as to why AR-15 weapons are their weapon of choice," she said.
"The guns are accurate. They have good handling. They're light. They're easy for women to hold. And most importantly, their appearance. An assault weapon in the hands of a young woman defending her babies in her home becomes a defence weapon."
Trotter added that "scary-looking guns" give women more courage when they're fighting "hardened, violent criminals" who have broken into their homes.
Trotter did not get many followup questions from senators.
Kelly, meantime, argued that improving the background check system in the U.S. should be a top priority, saying loopholes in the law "make a mockery" of the system. He also contended that stronger background checks could have prevented the mass shooting in Tucson, Ariz., that almost killed his wife in 2011.
LaPierre countered that the Obama administration has failed to enforce existing laws.
"Prosecuting criminals who misuse firearms works," LaPierre testified. "Unfortunately, we've seen a dramatic collapse in federal gun prosecutions in recent years."
Johnson pointed out, however, that federal prosecutions are falling because local prosecutions are on the upswing.
Gun control is a hot-button issue in the United States, where an estimated 45 per cent of the nation's households house at least one firearm.
Americans have a historic affection for guns stemming from a long-held distrust of government. Early settlers were pioneers and revolutionary rebels, and guns are therefore considered central to the American identity, particularly in the south and the West.
But gun control advocates insist that the Second Amendment of the U.S. Constitution, guaranteeing the right to bear arms, has been distorted by gun enthusiasts to a degree never intended by the country's Founding Fathers, who couldn't have imagined the firepower of today's guns.