The super PAC started by New York City Mayor Michael Bloomberg (I) is putting its weight behind former state representative Robin Kelly in Illinois's 2nd District special election, releasing a new ad that touts her stance on gun control and criticizes two of her opponents on the issue.

"Kelly will join President Obama to take on the NRA for effective background checks and to ban deadly assault weapons," says the narrator of the ad. It's the first time the organization, Independence USA PAC, has mentioned Kelly in a TV ad.

The group's newest ad comes as Obama is set to discuss guns and other issues on Friday in his hometown of Chicago, a city that has been plagued by violence. The 2nd District covers the South Side of Chicago as well suburbs to the city's south,

The spot also goes after two of Kelly's main competitors in the crowded Democratic field -- former congresswoman Debbie Halvorson and state Sen. Toi Hutchinson -- for receiving high marks from the National Rifle Association. The PAC has already spent over a million dollars on an ad campaign hitting Halvorson for her stance on guns.

"Debbie Halvorson and Toi Hutchinson both earned an A from the NRA. They can’t be trusted," the narrator of the new spot says.

Bloomberg, one of the nation's leading gun-control advocates, has used his political organization to back candidates who are in favor of tightening restrictions on guns.

The debate over guns has taken center stage in the Democratic primary campaign. The primary election will be held on Feb. 26, and will likely decide the district's next representative given its heavy Democratic tilt.

Independence USA did not release the size of its latest ad buy. The group said the post will air on cable and broadcast television.