Republican nominee Jesse Kelly is running against Democrat Ron Barber in a special election June 12 in Arizona's 8th District to replace Giffords in Congress. Giffords stepped down following a January 2011 shooting spree in which she was shot in the head and six others died.
The ad, created by the House Majority PAC, an independent group dedicated to supporting Democrats, features Kelly speaking words that could cause some controversy, USA Today reported Monday.
"And now she stands there with that smile and pretends to be some kind of hero. She's a hero of nothing," Kelly says in the ad.
Kelly made the remark in August 2010, months before Giffords was shot, the newspaper said.
Barber has said he plans to run his campaign with civility, but because super PACs are independent organizations, they do not coordinate advertising with him.