"It's still up the people who go into the booth and vote," Kelly said in a phone interview. "But I think those ads counterbalance the millions of dollars that the NRA (National Rifle Association) has spent to influence what they want to influence."
Halvorson also has been targeted by the Bloomberg PAC ads because of her opposition to an assault weapons ban. She bristled at the notion of Bloomberg wading into the election.
"He's got billions of dollars, he has always been very controlling and he wants to control a congressional seat," she said.
Halvorson supports background checks for gun purchases and registration of all firearms but opposes an assault weapons ban, saying law-abiding gun owners have Second Amendment rights and that a ban in Cook County hasn't prevented gun violence.
The special election was triggered by Jackson's resignation in November. Jackson faces a federal conspiracy charge for allegedly spending $750,000 in campaign money on personal expenses. He also was recently diagnosed with bipolar disorder.