New York Mayor Michael Bloomberg is again calling on the presidential candidates to come up with a specific plan on gun control.
He asked how anyone can run for the highest office in the country and not have a plan.
He said some people feel it's insensitive to talk about gun control as the nation mourns Colorado's victims. But he asked: "If not now, when?"
Bloomberg heads up a coalition of American mayors who support tighter gun control. The group has lobbied for stronger enforcement of existing laws.