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
Breezy and wet tonight as rain sweeps in from the west meaning a miserable start to Sunday morning.
BBC Political Editor Nick Robinson has revealed Labour tried to recruit him to be Ed Miliband's spin doctor in the run-up to the election.
Nasa has begun its countdown for a mission to discover whether life might exist on Jupiter's moon Europa.