Updated

A prominent gun control group on Thursday called on President Barack Obama and Republican challenger Mitt Romney to lead a search for solutions to gun violence, upping the political pressure on the White House hopefuls to take a decisive stance after the mass shootings in Colorado.

The Brady Campaign to Prevent Gun Violence said both candidates owe voters concrete plans, and that tens of thousands of people had already signed a petition urging them to speak up. The group's president, Dan Gross, said it was shameful for political leaders to play politics when lives could be saved.

"We truly believe, as a nation, we are better than this," said Gross. "We're better than a nation where shootings like the one in Aurora, Colo., happen with such frequency."

Obama and his aides were initially tepid about calling for stricter gun regulations after 12 people were killed inside the Colorado movie theater, aware of the implications on a tight presidential race in a country where gun-rights activists have a powerful voice. But on Wednesday, Obama embraced some degree of additional restrictions, including tougher background checks.

Gross challenged Obama to move beyond rhetoric, arguing that Americans can't be satisfied with words alone.

"The president said very similar things in his last campaign," Gross said. "A speech is not a plan. An endorsement of a measure is not a solution."

Romney has maintained that changing the nation's laws won't prevent gun-related tragedies.

Thirty-two people are killed by guns in the U.S. each day, according to the Brady Campaign, and 48,000 will die in the next president's term if the current pattern holds.

Gross said that while background checks and reinstating an expired federal ban on assault weapons are good places to start, it isn't the time to draw a line in the sand on specific policies. Rather, he said, the nation needs to step back, take stock of the issue and brainstorm solutions that could reduce violence without infringing on the right of individuals to lawfully own guns. He called on Obama and Romney to lead the search for those solutions.

"The only way we're going to translate those words into action, we believe, is to engage the American public in this conversation," Gross said.