The son of a woman, 86, who was killed when a gunman opened fire at a supermarket in Buffalo, New York, pressed the US Congress on Tuesday to act against "the cancer of white supremacy" after a spate of gun violence that has rocked the nation.
The testimony from Garnell Whitfield, son of Ruth Whitfield, comes as politicians rush to craft a bipartisan agreement on gun-control measures after shootings killed 10 people in Buffalo and 21 in Uvalde, Texas.
“What are you doing? You were elected to protect us,” Mr Whitfield told members of the Senate judiciary committee.
“Is there nothing that you personally are willing to do to stop the cancer of white supremacy and the domestic terrorism it inspires?
“If there is nothing then, respectfully, senators … you should yield your positions of authority and influence to others who are willing to lead on this issue.”
The hearing is the first of two this week as families of victims and survivors of the mass shootings in Buffalo and Uvalde appear at public hearings and events on Capitol Hill to show the human toll of America’s gun violence and urge Congress to act.
Senate majority leader Chuck Schumer said he was giving negotiators more time to strike a deal.
"Senator [Chris] Murphy has asked for some space to have the bipartisan talks continue, and I have given him that space," Mr Schumer said.
President Joe Biden on Tuesday met Mr Murphy, a Democratic senator who has played a key role in bipartisan negotiations over gun-control legislation.
Mr Biden last week called on Congress to ban assault-style weapons and high-capacity magazines, or to raise the minimum age to buy those weapons from 18 to 21.
But with most Republicans opposed to tighter gun controls, a bipartisan group of senators is seeking more modest proposals such as "red flag" laws that would keep firearms away from people who may do harm.
Also included in discussions are increased security at schools and wider access to mental health services.
After his meeting with Mr Biden, Mr Murphy said: "Obviously, we've still got work to do in the Senate."
Shortly after the Buffalo and Uvalde shootings, Senate Republicans blocked a bill that would have increased the federal government's ability to monitor and report on domestic terrorism in the US.
Tuesday's hearing focused on the "Great Replacement" theory, a white supremacist ideology that police say led a teenage gunman to fire on black shoppers at a supermarket in Buffalo, killing 10.
“My mother’s life mattered,” Mr Whitfield said. “Your actions here will tell us if and how much it mattered to you.”
On Wednesday, a US House committee is expected to hear from more victims' families and a pupil from Robb Elementary School, who covered herself in her dead friend's blood to avoid being shot by an 18-year-old gunman.
Agencies contributed to this report