Bloomberg, making his weekly appearance on John R. Gambling's radio show on WOR in New York hours after a mass shooting in Colorado, called on the presidential contenders to "stand up" and say what they plan to do about gun violence, The Hill reported.
"There are so many murders with guns every day, it's just got to stop," Bloomberg said. "And this is a real problem. No matter where you stand on the Second Amendment, no matter where you stand on guns, we have a right to hear from both of them concretely, not just in generalities -- specifically what are they going to do about guns?"
Bloomberg, a Democrat who switched to the Republican Party when he ran for mayor in New York, is now an independent.
Both Obama and Romney issued statements condemning the Colorado shootings but did not talk about policy. A 24-year-old man, James Holmes of Aurora, allegedly opened fire in a movie theater during the first showing of the new Batman movie early Friday, killing at least 12 people and wounding 38.
"The president believes we need to take common-sense measures that protect the Second Amendment rights of Americans while ensuring that those who should not have guns under existing laws do not get them," Obama spokesman Jay Carney said.
After the shootings in Tucson in 2011 that killed six people and left U.S. Rep. Gabrielle Giffords, D-Ariz., with severe head injuries, Obama refrained from using the massacre to call for more restrictions on guns, USA Today said.