A father whose six-year-old son was killed in the Connecticut school shooting has pleaded with members of a US Senate panel to ban assault weapons.
Struggling to fight back tears, Neil Heslin, a 50-year-old construction worker, urged lawmakers to come to an agreement on increased gun controls.
"I'm not here for sympathy," said Mr Neil, who said he grew up with guns and had been teaching his son, Jesse Lewis, about them. "I'm here because of my son."
"No person should have to go through what my family and other victims' families have had to endure," he added.
Jesse was among 20 children and six educators killed by 20-year-old Adam Lanza at Sandy Hook Elementary School in Newtown, Connecticut, on December 14.
His father spoke for 11 minutes, his voice barely audible and breaking at times, to the Senate Judiciary Committee that is deeply divided over the issue of gun control.
The panel was holding a hearing on a bill introduced by Senator Dianne Feinstein to ban assault weapons and ammunition magazines that carry more than 10 rounds.
Sen Feinstein and her allies said her measure would reduce the deaths such high-powered firearms can cause, but Republicans on the panel said the move would violate the constitutional right to bear arms and take guns away from law-abiding citizens who use them for self-defence.
Although he supports the US Constitution's Second Amendment right for citizens to have firearms, Mr Heslin said the amendment was written centuries before weapons as deadly as assault weapons were invented.
He recalled the morning of the Newtown shooting and said his son had told him "it's all going to be OK" as he dropped him off at the school gate.
The shooting revived the national conversation on guns and led to a move by the Obama administration to call for stricter gun laws.
But despite the massacre and other mass shootings, gun control legislation faces a difficult path through Congress.
The struggle was underscored when the Republican chairman of the House Judiciary Committee said he opposes universal background checks for gun purchases - a central piece of President Barack Obama's plan.
Representative Bob Goodlatte told reporters that the proposal could lead to creation of a federal gun registry - a claim the Obama administration has said will not happen.
The Senate Judiciary hearing was the committee's third since the Newtown tragedy.
Numerous relatives and neighbours of victims of Newtown, as well as other shootings at Aurora, Colorado, and Virginia Tech University filled the large hearing room.
Sen Feinstein, who helped create a 1994 assault weapons ban that expired in 2004, and other supporters cite studies showing use of the firearms in crimes diminished while the prohibition lasted.
A 2004 report said the proportion of gun crimes involving assault weapons dropped by up to 72% in five cities studied.
Opponents cite data from the same study showing assault weapons were used in only 2% to 8% of gun crimes, arguing that a ban would have little impact.
The study also estimated there were 1.5 million assault weapons owned privately in the US in 1994, and an estimated 30 million high-capacity magazines as of 1999, which critics say means exempting them would diminish a ban's effect.
Sen Feinstein's latest measure specifically bans 157 firearms but excludes 2,258 others in an effort to avoid barring hunting and sporting weapons.