Michael Bloomberg, the billionaire former mayor of New York City, has vowed to plough up to $50m (£30m) of his own money into a new organisation to support political candidates favouring gun control in the US and confront the political power of the National Rifle Association.

“We’ve got to make them afraid of us,” Mr Bloomberg, who left office in January, said in an interview with The New York Times. In 2012, the NRA spent about $20m trying to influence key election races across the country, as part of its effort to smother support for gun control in Congress.

The new group, to be called Everytown for Gun Safety, will operate primarily in 15 states, some where the gun lobby is dauntingly strong, like Texas, and others where signs of a backlash against guns are stronger.

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Above all, though, its mission will be to motivate Americans who may have become impatient with the country’s gun culture – particularly mothers and women – to go out and vote. Speaking on NBC News, Mr Bloomberg, 72, insisted his goal was not “gun control” as such, for example banning the sale of weapons, but seeing candidates elected who will support laws to stop the wrong people owning them – for example, through more stringent background checks at purchase.

“Nobody’s going to take anybody’s gun away,” he said. “Nobody’s going to keep you from hunting or target practice or protecting yourself. It’s just making sure that a handful of people who we all agree shouldn’t have guns don’t get their hands on them.”

While significant, Mr Bloombergs cash could at first help the NRA to galvanise its own supporters, who view the former mayor as a meddling nanny who tried to stop New Yorkers smoking and buying fizzy drinks. “He’s got the money to waste,” said Larry Pratt, leader of Gun Owners of America. “So I guess he’s free to do so. But I think he’s going to find out why his side keeps losing.”

Mr Bloomberg is already the national face of the gun-control lobby, with millions given to two existing groups – Mayors Against Illegal Guns and Moms Demand Action for Gun Sense in America – both of which will now be under the auspices of the new group.

A week away from its annual national convention, this year in Indianapolis, the NRA remains a mighty force. “They say, ‘We don’t care. We’re going to go after you’,” Mr Bloomberg said of it. “‘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’.”

Meanwhile, the recent record in Congress on tackling gun violence, even after the 2012 massacre at Newtown School in Connecticut, is desultory. With November’s mid-term congressional elections around the corner, Democrat leaders in the Senate have indicated they have no plans to push for even the most modest of new controls for fear it will hurt their candidates, particularly in conservative western states.

But Mr Bloomberg made clear that he was in it for the long haul. “You’ve got to work at it piece by piece,” he told the Times. “One mom and another mom. You’ve got to wear them down until they finally say, ‘Enough.’” Just as the NRA spends its money to assist candidates that are on its side, the new group will do the same, persuading supporters of those candidates to turn out. In the past, the bulk of Mr Bloomberg’s money has gone to television advertising.

In the NBC interview, he used language straight from the NRA playbook, stressing that his group would reward candidates “who are protecting lives, and make sure that those who are trying to keep people from being protected lose elections”.