Mark Barden, whose son Daniel was among those killed in the Newtown massacre, has said families of the victims are heartbroken at the Senate's blocking of gun ownership legislation but will continue to campaign for stronger weapon controls.
He issued an emotional plea at the White House after a plan aimed at expanding background checks for gun buyers failed to receive enough support in a vote.
With President Obama looking on, Mr Barden said: "We always knew this would be a long road. We don't have the luxury of turning back."
More top news
Uber may have broken UK law when it hushed up a major hack affecting 57 million customers and drivers worldwide, a minister has said.
The UN has described the treatment of Rohingya Muslims in Myanmar as a 'textbook case of ethnic cleansing'.
A UK study will explore whether dementia is more common in ex-professional footballers than in the normal population.