Tucson Mayor Bob Walkup urged mayors across the country to take a more civil tone in their political discourse and encouraged them to a sign a pledge promising to do so.

Walkup's remarks, delivered to the U.S. Conference of Mayors winter meeting in Washington, came 11 days after a gunman wounded U.S. Rep. Gabrielle Giffords and killed six others at a Tucson grocery store. Pundits have debated whether the increasingly divisive rhetoric used in the political sphere may have played a role in the motivation behind the attack.

Walkup did not explicitly take that position, but he encouraged the more than 230 mayors that attended Wednesday's meeting to join him in signing a "civility accord" in which they pledged to avoid rhetoric intended to humiliate, de-legitimize, or question the patriotism of those whose views differ from their own.

Walkup said in the days following the attack, he received calls from Philadelphia Mayor Michael Nutter, Los Angeles Mayor Antonio Villaraigosa and Burnsville, Minn., Mayor Elizabeth Kautz -- the president of the U.S. Conference of Mayors -- who all asked how they could help.

"Why don't we start talking about how we can treat each other better," Walkup said he replied.

He emphasized that the mayors' pledge should extend beyond the political realm and be applied to their daily discourse. "Most of us are elected officials only for the moment," Walkup said, "but we're human beings forever."

Outgoing Chicago Mayor Richard Daley, who was given an award by the U.S. Conference of Mayors, used his acceptance speech to call for stricter gun control laws in light of the Tucson shooting.

Daley said gun violence is "overtaking" the country. "We should re-discuss the issue of people arming themselves… and feeling protected by a gun and not by words," Daley said.