CARSON CITY, Nev. » John W. Griffin is a fast-talking, whiskey-loving, fifth-generation Nevadan who spends his days as a lobbyist courting lawmakers in Stetsons. He advocates for luxury casinos, once brokered a dispute between a brothel and a nightclub, and has helped feuding families resolve tussles over cattle crossings.

Now he is representing the ultimate city slicker, Michael R. Bloomberg, the mayor of New York, who, undaunted by defeat in Congress, is taking his campaign for stricter gun laws to the nation’s state capitals, including here, where a bill to expand the use of criminal background checks is before the state Legislature.

"I thought, ‘Heck, that’s going to be a tough battle,’" Griffin said. "But for a man with unmatchable resources, there’s good reason to be hopeful."

Fortified by several million dollars in contributions that have come in since the Newtown, Conn., school massacre in December, Mayors Against Illegal Guns, the national coalition Bloomberg co-founded and finances, says it has deployed more than 50 people across the country, building grass-roots organizations and dispatching foot soldiers to pressure local politicians.

In Washington state, where a Bloomberg-backed background-checks bill was defeated in the Legislature this year, the coalition is assisting with a ballot initiative on the same issue. In Oregon, the group has hired lobbyists to revive long-stalled legislation to regulate private gun sales. In Colorado, where the coalition helped pass stricter gun laws this year, it is preparing to defend lawmakers against a recall effort pushed by the National Rifle Association.

Bloomberg faces an uphill battle – many of the states he seeks to influence are places where guns are dear and New York is not. He is going up against well-organized networks of gun enthusiasts, with scores of rural voters eager to block his every move.

Some lobbyists working on behalf of the mayors’ coalition say they have been given a piece of cautionary advice: avoid mentioning Bloomberg’s name, for fear that it could alienate potential allies. "I don’t think we’ve ever used the word Bloomberg," Griffin said.

Although the coalition says it did not instruct lobbyists to omit the mayor’s name, it is clear that Bloomberg’s high profile has made him the focal point of much of the anger that has accompanied the debate over gun rights. On Wednesday, New York City authorities revealed that the mayor and his coalition had been sent letters tainted with the deadly poison ricin, prompting a federal investigation that is examining whether the letters were linked to a similar one that had been addressed to President Barack Obama.

Despite repeated setbacks to his efforts to pass gun laws, Bloomberg has vowed to accelerate his campaign, even after his mayoralty ends in December. The issue is important not only nationally, but also locally, his aides say, because 85 percent of the guns used in crimes in New York City are acquired out-of-state.

"We don’t give up," said John Feinblatt, who oversees Mayors Against Illegal Guns and serves as Bloomberg’s chief policy adviser. "We’re here for the long haul."

The coalition would not offer details on how much it is spending on state efforts, and Griffin, who was approached a few weeks ago by an emissary for the group, declined to say how much his firm was being paid. The coalition has spent tens of thousands of dollars on television ads in Nevada – a relatively inexpensive media market.

The mayor, whose net worth is estimated at $27 billion, has repeatedly demonstrated his willingness to use his money to fight for gun control. Last year, he bankrolled an $11 million campaign largely focused on building support for federal regulations to reduce gun violence, and this year, his political action committee spent $2.3 million to defeat candidates who opposed gun control in a special election for an Illinois House seat. Also this year, the mayors’ coalition hired a team in Minnesota and pushed, unsuccessfully, for expanded use of background checks. It helped lead successful efforts in more liberal states, including Maryland, Delaware, and Connecticut.

In Carson City, lawmakers credit Bloomberg with jump-starting a gun bill that had stalled in Nevada, even though both chambers of the Legislature are controlled by Democrats. The bill, modest by standards in more liberal states, would require criminal background checks in private gun sales, including at gun shows and online; currently, background checks are mandatory only if a gun is purchased through a licensed dealer.

Bloomberg’s team coordinated a phone call campaign to legislators, flew in families affected by gun violence to meet with lawmakers, and provided advice on minimizing the cost of background checks.

The effort has not been without hiccups: Michael Roberson, a Republican who is the Senate minority leader, was infuriated when he learned the group had gone to his home to urge his wife to support the guns bill. A flier distributed by the coalition asked voters to call the senator to ask "why he wants to make it easy for convicted felons, domestic abusers, and the dangerously mentally ill to buy guns."

But the broader bill, with background checks, passed the state Senate late in May, and the measure now has enough support to pass the Assembly. This weekend, in the final days of the Nevada Legislature’s session, Bloomberg’s team is concentrating on winning over a handful of Assembly Republicans, hoping a show of bipartisan support would prompt Gov. Brian Sandoval, a Republican, to reconsider a threatened veto. The coalition is also airing a television ad urging Nevadans to ask Sandoval to sign the legislation.

At one point, 11 lobbyists for the coalition were squaring off with one lobbyist for the National Rifle Association at the Nevada capital. But Billy Vassiliadis, who runs a prominent lobbying firm, said he quickly dropped out of the effort after deciding that Bloomberg’s battle was unwinnable.

"Taking part in a production, rather than actual work, was not in our interest," Vassiliadis said. He said Bloomberg needed to spend more time educating the public about the benefits of background checks.

But Griffin, 40, has stuck with Bloomberg, whom he previously knew only from watching the MSNBC show "Morning Joe." He and his team have become something of a spectacle in the halls of the Legislature, mocked by some as puppets of a billionaire, admired by others as symbols of smart campaigning.

Griffin has advised Mayors Against Illegal Guns on advertisements, gathered cellphone numbers of lawmakers to pass along to the coalition, even noting that one lawmaker was an avid country music fan and might benefit from a call from a celebrity in the mayor’s orbit.

Some Republicans believe Bloomberg’s involvement has stalled attempts at a compromise that could have won the governor’s support.

"Bloomberg is engaged in too many crusades," said Assemblyman Wesley Duncan, one of the Republicans courted by the mayors’ coalition. "He’s lost credibility. Now you have people from out-of-state telling Nevadans what to do, instead of activists from within."

And John Ellison, an assemblyman who represents rural parts of northeast Nevada, said: "I have the right to self-protection. I’m not going to allow Bloomberg or whoever to take those rights away from me."

Nevada, where the words "battle born" appear on the state flag, has a history of support for gun rights, but the state is changing fast – its urban centers are booming, and Hispanics now make up 27 percent of the population.

The state has also seen gun violence up close. In 2011, about 2 miles from the state Legislature, a gunman killed four people as they ate breakfast at an IHOP restaurant and then killed himself.

Justin C. Jones, a Democratic state senator from Las Vegas who sponsored the background checks bill in the Nevada Legislature, said Bloomberg had successfully revived an issue that might easily have been ignored.

Jones said he hoped Bloomberg would continue to be involved in Nevada politics. He faces re-election next year – he won by just 301 votes in 2012 – and in the past, Bloomberg has offered political and financial support to candidates who back his policies.

"It never hurts," Jones said, "to have friends with money."