Romney: Obama will erode the rights of gun owners

"Our disappointment is that his voice is really yet to be heard in that conversation," Gross said. He said Romney is pandering to the NRA, a group he accuses of abetting the killings of thousands of people.

Neither Romney nor other NRA speakers — former presidential contender Rick Santorum and still-trying candidate Newt Gingrich were among them — alluded to the high-profile Martin case. A volunteer neighborhood watchman has been charged with second-degree murder for fatally shooting the unarmed teenager, who was walking in a gated community.

The NRA strongly backed Florida's "stand your ground" law, at the heart of the unfolding case.

Romney spokeswoman Andrea Saul said Romney "believes that efforts to craft 'stand your ground' legislation should be left up to the individual states."

When Romney ran successfully for Massachusetts governor in 2002, the NRA gave his Democratic opponent a higher rating on gun-rights issues but made no endorsement.

Massachusetts quadrupled its gun-licensing fee while Romney was governor. He signed a law that made permanent a ban on assault-type weapons, although it was coupled with some measures backed by gun-rights groups.

As he was considering his first presidential run in 2006, Romney became a lifetime NRA member.

Romney drew snickers in 2008 by claiming he sometimes hunts "small varmints." He showed more humility and humor last month in Alabama, where he said he hoped to go hunting with a friend who "can actually show me which end of the rifle to point."

Gingrich, who addressed the NRA convention after Romney, said the United Nations should adopt a treaty "to extend the right to bear arms to every person on the planet." Such "human rights," he said, would reduce rapes and child killings worldwide.