The Mayors Against Illegal Guns coalition, co-chaired by New York City mayor Michael Bloomberg, launched a new attack ad Friday in which the mother of an Aurora theater shooting victim speaking out against Republican Arizona Sen. Jeff Flake.

The coalition’s new ad, entitled “My Son,” features an interview with Arizona resident Caren Teves, mother of Aurora, Colorado theater shooting victim Alex Teves. Teves explains that she and her husband wrote to Flake urging him to support strengthened background checks. Though Teves claims that Flake told her he also supported strengthening background checks, Flake shortly afterward voted against the Manchin-Toomey background checks bill that was criticized for taking the first step toward national gun registration.

“The issue isn’t just background checks. It’s keeping your promise. Senator Flake didn’t,” according to Teves, who never claims in the ad that Flake promised to specifically vote for the Manchin-Toomey bill. The ad will run through May 30 in the Phoenix and Tucson media markets.

It is unclear how much impact the ad will have with residents in the traditionally conservative state of Arizona.

Teves previously garnered press attention for attacking Republican Sen. John McCain at a town hall in Phoenix in February. Teves told the liberal outlet Talking Points Memo that she was “appalled” by McCain’s response to her statement supporting an assault weapons ban.

“I can tell you right now you need some straight talk. That assault weapons ban will not pass the Congress of the United States,” McCain told her.

Bloomberg’s anti-gun coalition previously targeted New Hampshire Republican Sen. Kelly Ayotte with an attack ad and a pressure campaign also featuring a town hall appearance by the relative of a mass shooting victim.

Mayors Against Illegal Guns reportedly sent 27-year old activist Erica Lafferty, daughter of slain Sandy Hook elementary school principal Dawn Hochsprung, to Ayotte’s town hall meeting, where she asked a confrontational question and then stormed out of the event when Ayotte responded that mental health initiatives, not gun control measures, are the proper solutions to episodes of mass violence. Lafferty’s stunt earned wide media coverage from outlets including NBC News and the Huffington Post, and was praised by Chris Matthews of MSNBC.

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