DENVER (AP) — The father of a Columbine shooting victim who has since become a prominent gun-control advocate is pushing for increased background checks for guns.

Tom Mauser, father of Daniel Mauser, joined Colorado Senate Democratic Leader John Morse of Colorado Springs Thursday to call for Congress to tighten rules for background checks for gun purchases.

A rally at the state Capitol launched a “Fix Gun Check” two-day tour through Colorado. Gun-control advocates planned to drive a mobile billboard calling for congressional action.

Mayors from big and smaller cities have joined the effort, including New York Mayor Michael Bloomberg. Denver Mayor Bill Vidal is the coalition’s only listed member in Colorado.

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