Michael R. Bloomberg, making his first major political investment since leaving office, plans to spend $50 million this year building a nationwide grass-roots network to motivate voters who feel strongly about curbing gun violence, an organization he hopes can eventually outmuscle the National Rifle Association.
Mr. Bloomberg, the former mayor of New York, said gun control advocates need to learn from the N.R.A. and punish those politicians who fail to support their agenda — even Democrats whose positions otherwise align with his own.
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"They say, 'We don't care. We're going to go after you,' " he said of the N.R.A. " 'If you don't vote with us we're going to go after your kids and your grandkids and your great-grandkids. And we're never going to stop.' "
He added: "We've got to make them afraid of us."
The considerable advantages that gun rights advocates enjoy — in intensity, organization and political clout — will not be easy to overcome. Indeed, Mr. Bloomberg has already spent millions of dollars trying to persuade members of Congress to support enhanced background check laws with virtually nothing to show for it.
What is more, for many gun owners, the issue is a deeply personal one that energizes them politically, said Larry Pratt, executive director of Gun Owners of America, who dismissed the mayor's plans.
"He's got the money to waste," Mr. Pratt said. "So I guess he's free to do so. But frankly, I think he's going to find out why his side keeps losing."
The N.R.A. had no comment.
Mr. Bloomberg's blueprint reimagines the way gun control advocates have traditionally confronted the issue. Rather than relying so heavily on television ad campaigns, Mr. Bloomberg will put a large portion of his resources into the often-unseen field operations that have been effective for groups like the N.R.A. in driving single-issue, like-minded voters to the polls.
Women, and mothers in particular, will be the focus of the organizing and outreach, a path that he and his advisers have modeled after groups like Mothers Against Drunk Driving.
The plans call for a restructuring of the gun control groups he funds, Mayors Against Illegal Guns and Moms Demand Action for Gun Sense in America. They will be brought under one new umbrella group called Everytown for Gun Safety.
The strategy will focus not on sweeping federal restrictions to ban certain weapons, but instead will seek to expand the background check system for gun buyers both at the state and national levels.
The $50 million could be significant: In recent years, the N.R.A. has spent only $20 million annually on political activities. The political groups affiliated with the billionaire Koch brothers, who are seeking to help Republicans take over the Senate, have spent about $30 million in the last six months.
The group will zero in on 15 target states, from places like Colorado and Washington State, where gun control initiatives have advanced recently, to territory that is likely to be more hostile like Texas, Montana and Indiana. They have set a goal of signing up one million new supporters this year on top of the 1.5 million they already have.
Previous efforts by Mr. Bloomberg to push gun control have touched off tensions with national Democratic leaders, because he has run negative ads against incumbent Democrats whom he views as insufficiently supportive of gun control. The Democratic leaders argue that Mr. Bloomberg threatens to hand control of the Senate to Republicans, which they say would doom any hope of passing gun control legislation.
Mr. Bloomberg dismissed those fears, saying he was concerned only with the long term.
"You can tell me all you want that the Republicans would be worse in the Senate than the Democrats," he said. "Maybe they would. But that's not what we're talking about here."
Underscoring his desire to work with both parties, Mr. Bloomberg is bringing on a new advisory board with prominent Republican and Democratic figures. Tom Ridge, the former Pennsylvania governor and Homeland Security secretary under President George W. Bush; Eli Broad, the philanthropist; Warren Buffett, the investor; and Michael G. Mullen, the former chairman of the Joint Chiefs of Staff under both Mr. Bush and President Obama, will all be board members.
Mr. Bloomberg acknowledged that his new efforts would require a dedication not just of money but also of time — two things he now has in abundance.
"You've got to work at it piece by piece," he added. "One mom and another mom. You've got to wear them down until they finally say, 'Enough.' "
He was also dismissive of skeptics who might question whether he could ever build an organization that rivaled the N.R.A. And he seemed unaware of, or unwilling to acknowledge, the ways in which his own persona — of a billionaire, Big Gulp-banning former mayor of New York — could undercut his efforts, especially in rural, conservative states.
"I don't know what your perception is of our reputation, and mine, the name Bloomberg around the country," he said. But every place he goes, he added, "You're a rock star. People yelling out of cabs, 'Hey, way to go!' "
His financial commitment to reducing gun violence could grow. When asked how much he was willing to spend, he tossed out the $50 million figure out as if he were describing the tip he left on a restaurant check.
"I put $50 million this year, last year into coal, $53 million into oceans," he said with a shrug, describing his clean energy and sustainable fishing initiatives. "Certainly a number like that, $50 million. Let's see what happens."
The key to whether they can be effective, the mayor and his advisers said, will be turning out female voters, the sought-after swing bloc that has been pivotal in recent elections.
"Right now, women, when they go to the polls, they vote on abortion, they vote on jobs, they vote on health care," said Shannon Watts, founder of Moms Demand Action. "We want one of those things to be gun violence prevention."
Mr. Bloomberg was introspective as he spoke, and seemed both restless and wistful. When he sat down for the interview, it was a few days before his 50th college reunion. His mortality has started dawning on him, at 72. And he admitted he was a bit taken aback by how many of his former classmates had been appearing in the "in memoriam" pages of his school newsletter.
But if he senses that he may not have as much time left as he would like, he has little doubt about what would await him at a Judgment Day. Pointing to his work on gun safety, obesity and smoking cessation, he said with a grin: "I am telling you if there is a God, when I get to heaven I'm not stopping to be interviewed. I am heading straight in. I have earned my place in heaven. It's not even close."
—By Jeremy W. Peters of The New York Times