Rugged individualism personified, the bearded white man wears a camouflage hat and sits in a pickup truck bed as he cradles a pump-action shotgun.

“I believe in the Second Amendment, and I’ll fight to protect it, but with rights come responsibilities,” he says in one of the advertisements flooding Georgia televisions this week paid for by billionaire New York City Mayor Michael Bloomberg’s Mayors Against Illegal Guns. “That’s why I support comprehensive background checks.”

Bloomberg’s push — including a rally in Atlanta next week — is aimed primarily at two people: Republican U.S. Sens. Johnny Isakson and Saxby Chambliss, who could have the chance to vote on expanded background checks for gun purchases in the coming weeks.

Background checks are now the primary goal for gun control advocates as a legislative response to the December massacre at a Connecticut elementary school. Their hopes have faded for a revived ban on certain military-style weapons or large gun magazines amid resistance in the Senate from Republicans and red-state Democrats.

A universal background check bill that emerged from a Senate committee is opposed by the powerful National Rifle Association, as well as Chambliss. Isakson, who backed background checks in Georgia when he was in the state Senate, said he would wait to see what gets to the floor before declaring a position, as a bipartisan compromise remains possible.

Georgia is dominated by gun-friendly Republicans, and the state Legislature sought to expand gun rights this year, though the bill died Thursday night as the two chambers could not agree on restrictions for allowing guns on college campuses. But a poll that Mayors Against Illegal Guns commissioned in February showed 91 percent of Georgians support mandatory criminal background checks for all gun purchases.

Background checks now are required only for licensed dealers, leaving what advocates call a gaping loophole for “private sales” at gun shows and on the Internet.

A bill authored by Sen. Charles Schumer, D-N.Y., would mandate background checks for all gun transactions, with exceptions for immediate family and sharing guns at a range or while hunting. It would mandate gun owners report a lost or stolen gun within 24 hours.

Opponents of universal background checks say it would be onerous for transactions between close friends, for example, and the NRA has warned that it could be a pathway to a federal gun registry — even though that is explicitly forbidden by law.

“Any bill that criminalizes private transfers between two law-abiding Americans is a nonstarter with us,” NRA spokesman Andrew Arulanandam said.

Isakson and Chambliss both earned “A” ratings from the NRA in their most recent re-election campaigns, but Bloomberg’s group thinks Isakson’s vocal support for background checks and Chambliss’ retirement next year might make them persuadable to the cause.

“I supported the background-check law that passed in Georgia,” Isakson said of the 1995 state law that was supported by the NRA. “That was an instant check with no waiting period and no ban. So we’ll wait to see what the final product is here.”

In the U.S. House in 1999 Isakson and Chambliss voted against a universal background check.

Chambliss said he supports keeping guns out of the hands of criminals and people with serious mental illnesses, but he thinks the Schumer bill does not do the job.

“My review with the proposal that came out of committee is it almost punished gun owners, folks who are trying to do the right thing,” Chambliss said.

The bill passed on a party-line vote, and 60 votes to break a Republican filibuster will be difficult to come by. Sen. Joe Manchin, D-W.Va., is trying to broker a compromise between leading Democrats and the NRA on the issue. Arulanandam would not comment on the discussion or whether the NRA could support any background check expansion, but he said the background check system “has gaping holes in it” and must be fixed before it can be expanded.

Among the executive orders President Barack Obama signed in January to address gun violence are efforts to improve incentives for states to contribute to the background check system and assess how the system can work around health privacy laws.

Senate Majority Leader Harry Reid said an assault weapons ban and magazine limit could get votes as amendments, but they are likely to be defeated. There is bipartisan backing for a crackdown on gun trafficking and spending more on school security.

Mayors Against Illegal Guns is spending $12 million on this ad campaign in 13 states. The group also dropped $2 million in ads last month in the Chicago area on a special election for the U.S. House, boosting a gun control advocate to victory over an NRA-endorsed candidate.

The NRA has its own resources. In 2012, it spent $25.2 million in independent advertising, $1.46 million in political donations and $2.98 million on lobbying, according to the nonpartisan Center for Responsive Politics.

While the NRA and Mayors Against Illegal Guns are positioning themselves as foils, MAIG Political Director Mark Glaze emphasized that according to his group’s polling even the majority of NRA members support universal background checks.

The NRA says it has nearly 5 million members nationwide, but it would not give out figures for Georgia. Mayors Against Illegal Guns says 1.5 million people have signed up on its website for updates, and it has recruited 12 Georgia mayors to the cause, including Atlanta Democrat Kasim Reed and Roswell Republican Jere Wood.

“We’re trying to do everything we can to impress upon the senators that this is what the survivors want, this is what the public wants,” Bloomberg said of universal background checks last week on NBC’s “Meet the Press.” “I don’t think there’s ever been an issue where the public has spoken so clearly, where Congress hasn’t eventually understood and done the right thing.”