By John Fritze

Promising to "rebuild the heart of America's cities," former Gov. Martin O'Malley used an appearance at a meeting of the nation's mayors on Sunday to call for a federal ban on assault weapons and stricter regulations on gun purchases.

O'Malley, who is seeking the Democratic nomination for president, told the annual meeting of the U.S. Conference of Mayors that the massacre at a black church in South Carolina last week demanded action from Washington.

"I heard some elected officials say this week, 'laws can't change this,'" O'Malley told the group in San Francisco.

"Actually, they can," he said. "How many senseless acts of violence do we have to endure as a people before we stand up to the congressional lobbyists of the NRA?"

The former Baltimore mayor also joined the chorus of elected officials who have called on officials in South Carolina to remove the Confederate flag from the grounds of the state house in Columbia. The battle flag flew above the capitol from 1962, at the height of the Civil Rights Movement, until 2000, when it was removed to its current spot on the adjacent grounds.

"If the families of Charleston can forgive, can let go of their anger, is it really too much to ask the state government officials of South Carolina to retire the Confederate flag to a museum?" he said.

O'Malley, who served in City Hall from 1999 to January 2007, chaired a homeland security panel at the Conference of Mayors during his tenure. The position gave him a platform from which to criticize the Bush administration over homeland security funding, which helped to elevate his national profile.

Former Secretary of State Hillary Clinton, the front runner in the race for the Democratic nomination, told the mayors on Saturday that she supports "common-sense" gun laws, but she did not offer specifics.

Both politicians were giving their first major address since a gunman shot nine people during a bible study Wednesday at the historically black Emanuel A.M.E. Church in Charleston. Authorities say 21-year-old Dylann Storm Roof has confessed to the killings; he has been charged with nine counts of murder.

The conference was a friendly place for the presidential candidates to make their pitch: Big city mayors have been among the most vocal advocates for stronger federal gun laws.

O'Malley's address expanded on a series of positions he outlined in an email to supporters last week. In addition to the assault weapons ban, the former governor said he supported stronger background checks and closing second-hand purchasing loopholes, such as at gun shows. He touted several gun measures approved in Maryland when he was governor.

"The most poisonous force in American politics is not bad people who do bad things, it is good people who do nothing," he said. "The shrug of the shoulders, the resignation that somehow this is the best we can do."

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