It's been more than a decade since gun control advocates had a realistic hope of getting the type of legislation they seek, despite predictions that each shocking outburst of violence would lead to action.
In his remarks, Obama acknowledged a national pattern of calling for tougher gun restrictions in the wake of violent crimes but not following through.
"Too often, those efforts are defeated by politics and by lobbying and eventually by the pull of our collective attention elsewhere," he said.
Romney was pressed on gun control during an interview with NBC News in London, where he is attending the Olympics and kicking off a three-country foreign trip. The presumptive Republican nominee said changing laws won't "make all bad things go away."
Romney was asked about his tenure as Massachusetts governor, when he signed a bill that banned some assault-style weapons like the type the Colorado shooter is alleged to have used. At the time, Romney described such guns as "instruments of destruction with the sole purpose of hunting down and killing people."
Asked if he stood by those comments, Romney mentioned the Massachusetts ban but said he didn't think current laws needed to change.
"I don't happen to believe that America needs new gun laws. A lot of what this ... young man did was clearly against the law. But the fact that it was against the law did not prevent it from happening," Romney said.
Authorities have said the suspected Colorado shooter, James Holmes, methodically stockpiled weapons and explosives at work and home in recent months. He bought thousands of rounds of ammunition and a shotgun, a semiautomatic rifle and two Glock pistols, authorities said.
Obama addressed the nationwide troubles in front of the Urban League in part because blacks, who make up the bulk of the organization's membership, have been disproportionately affected by gun violence. While mass shootings like the one in Colorado receive widespread attention, Obama said roughly the same number of young people are killed in the U.S. by guns every day and a half.
"For every Columbine or Virginia Tech, there are dozens gunned down on the streets of Chicago and Atlanta, and here in New Orleans," he said. "For every Tucson or Aurora, there is daily heartbreak over young Americans shot in Milwaukee or Cleveland."
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