Ads from the Bloomberg-funded pro-gun control organization will be running in Alaska, Arkansas and North Dakota, three states with Democratic senators who voted against a bill that would require background checks before gun purchases.
Aides of Senate Majority Leader Harry Reid, D-Nev., met recently with Bloomberg's aides to warn them that such an effort may backfire and the Democrats could lose control of the chamber, several people knowledgeable about the situation told Politico.
Mayors Against Illegal Guns is moving as many as 60 field organizers into about a dozen states of senators of both parties voted against bill, trying to build an infrastructure and countering gun rights groups such as the National Rifle Association, Politico reported Tuesday.
Gun control legislation gained momentum since last December's shooting at Sandy Hook Elementary School in Newtown, Conn., in which 20 children and six adults were killed.
Four Senate Democrats -- Mark Pryor of Arkansas, Max Baucus (who is retiring) of Montana, Mark Begich of Alaska and Heidi Heitkamp of North Dakota -- joined with Republicans to oppose the bill, drawing protests from gun-control advocates and complaints from the White House.
Senate leadership said they'd rather see Bloomberg's organization channel its efforts differently, such as working to re-elect red-state Democrats, such as Sens. Mary Landrieu of Louisiana and Kay Hagan of North Carolina, who supported the bill.
But, Politico said, Mayors Against Illegal Guns will run radio ads in Arkansas targeting the African-American community, "without which Mark Pryor doesn't have a prayer of getting re-elected," said Mark Glaze, the organization's director.
Senate Democrats have urged Bloomberg and other gun control advocates to focus on trying to get Republicans -- such as Sen. Kelly Ayotte of New Hampshire -- to change their vote.
Americans for Responsible Solutions, founded by former U.S. Rep. Gabrielle Giffords, D-Ariz., a gunshot survivor, is running radio ads in Kentucky and New Hampshire attacking Senate Minority Leader Mitch McConnell, R-Ky., and Ayotte for opposing the measure. The NRA countered with ads praising the lawmakers.
"I think that's one thing the American people are frustrated about, these purity tests," Pryor said. "Quite honestly, I'm here to represent Arkansas. I think people on all sides, in all parties and all groups, they need to go back to civics class and maybe read the Constitution and realize we're here to represent our states and the people who sent us to Washington."