WASHINGTON -?The politics of guns leapt to the top of the presidential race Wednesday, as President Barack Obama embraced some degree of control of weapons sales and Republican Mitt Romney seemed to suggest an alleged mass killer in Colorado had obtained his weapons illegally even though he hadn't.

Speaking to a mostly black audience in New Orleans, Obama said he would seek a consensus on combating violence. He said some responsibility also rests with parents, neighbors and teachers to ensure that young people "do not have that void inside them."

Obama's remarks came five days after the movie theater shooting in Aurora, Colo., that left 12 dead and dozens wounded. He pledged to work with lawmakers of both parties to stop violence — not only the sudden massacres that have bedeviled the nation, but also the steady drip of urban crime that has cost many young lives.

The president called for stepped-up background checks for people who want to buy guns and restrictions to keep mentally unbalanced individuals from buying weapons. He said those steps "shouldn't be controversial, they should be common sense."

Romney, meanwhile, said many of the weapons deployed by the shooting suspect in Colorado were possessed illegally and that changing laws wouldn't prevent gun-related tragedies. His comments added a confusing layer to the debate because authorities say the firearms that James Holmes allegedly used to kill 12 people were obtained legally.

"This person shouldn't have had any kind of weapons and bombs and other devices, and it was illegal for him to have many of those things already," Romney told NBC News in an interview in London. "But he had them. And so we can sometimes hope that just changing the law will make all bad things go away. It won't."

Authorities say Holmes broke no laws when he bought an assault-style rifle, a shotgun and Glock handgun, and he passed the required background checks.

Aides to Romney said the former Massachusetts governor was alluding only to homemade bombs, reportedly used as attempted booby-traps in Holmes' apartment, when he spoke of items "illegal for him to have."

"The illegality the governor is referencing is the ordinances, the devices that were in the home," said campaign spokesman Danny Diaz. "He was not referencing the weapons carried to the theater."

In a separate interview with KRNV-TV in Nevada, Romney seemed more precise. He said Holmes "had various incendiary devices, bombs of some kind. The idea that saying those things, of course, were illegal, but he had them, simply passing laws does not make the threat of an individual who is deranged, disappear."

Romney's campaign acknowledged Wednesday that Holmes' gun purchases apparently were legal.

Aurora authorities disassembled the booby traps in the apartment, and they did not explode. It's unclear if the suspect obtained the bomb materials illegally, but it's against Colorado law to build an explosive device.

NBC News anchor Brian Williams pressed Romney about his tenure as Massachusetts governor, when the presumptive GOP nominee signed a bill that banned some assault weapons like the type Holmes 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.

Obama, speaking to the National Urban League, said, "We should leave no stone unturned and recognize that we have no greater mission that keeping our young people safe."

"We must also understand that when a child opens fire on other children, there's a hole in his heart that no government can fill," he said.