AUGUSTA, Maine — Proponents of expanding background checks for gun purchases on Saturday formally kicked off a campaign that has been under the radar so far, but will be heavily watched by national observers through November.

It’ll be one of two key national races this year on the same subject, pitting a group co-founded by billionaire former New York City Mayor Michael Bloomberg as a response to mass shootings in 2014 against the group it was meant to target — the National Rifle Association.

Right now, federal law already mandates background checks when guns are purchased through federally licensed dealers. But they’re not required for private transactions or at all gun shows.

The Maine proposal would require background checks in those situations, sending buyers and sellers of guns to gun dealers to run checks, except in transfers between family members, while people are hunting or shooting for sport, for self-defense or in other circumstances.

Eleven states have “universal” background check laws, according to the American Academy of Pediatrics. But Washington was the first to pass them at the ballot in 2014 after a campaign led by the Bloomberg group, Everytown for Gun Safety.

The same group is behind this year’s campaigns in Maine and Nevada, and it likely will spend millions in a heavily nationalized campaign against the NRA. But while the issue may have national support, it could run into resistance in a pro-gun Maine.

The pro-background check campaign starts its bid in earnest with a massive fundraising head start — nearly all of it funded by Everytown.

Maine Moms Demand Action for Gun Sense — the ballot question committee backing the referendum — starts with a wide money lead: It raised nearly $1.3 million from 2015 through March’s end, with 95 percent of that coming from Everytown, the Bloomberg group, according to state campaign finance records.

Advocates of the policy include police and family members of gun violence victims, headlined by Judi and Wayne Richardson of South Portland, whose daughter, Darien, died after being wounded in a unsolved 2010 home invasion in Portland by a gun transferred without a background check.

Gun-rights groups are starting to organize against the effort. David Trahan, executive director of the Sportsman’s Alliance of Maine, said his group will be part of a coalition led by the NRA. An NRA spokesman, Lars Dalseide, said the group will be “on the frontlines battling this out until November.”

The same groups fighting the Everytown effort in Maine martialed gun-rights conservatives to defeat ballot questions that would have banned bear baiting, hounding and trapping in 2004 and 2014. Through Election Day in 2014, opponents outraised bear-baiting foes.

But that was a different issue, and this time, Trahan said it’ll be “an uphill battle” to match them, and “I just don’t believe that we’ll be able to raise that kind of money.”

“Our difficulty is mainly going to be educating people about why we don’t support the referendum,” he said.

Background checks poll well, but they’re largely untested at the ballot and won’t be a slam dunk in Maine, with a strong gun culture and low firearm crime.

Everytown often cites consistent polling data showing national support for background checks at 90 percent or higher. But only a narrow majority of Americans say it’s more important to control gun ownership than protect gun rights in a July survey from the Pew Research Center.

The disconnect could be attributed to misperceptions about existing gun laws. For example, a recent Yale University survey found that 41 percent of Americans already think universal background checks are the law.

In Washington state, they passed with 59 percent support. However, the gun and sporting culture there isn’t what it is in Maine — where more than 41 percent of adults were estimated to have guns in 2002 compared with 36 percent in Washington, according to the pediatrics academy.

Gun rights advocates will argue that Maine doesn’t have a particular problem with gun violence: In 2011, it had the fifth-lowest rate of firearm use in crimes in the country at 14.2 percent, which was less than half the national average, according to the University of Southern Maine. But Everytown and the Richardsons will make a case that things could always be safer.

So, while the policy could be a winner nationally, Maine’s culture and the perception that this isn’t an urgent problem in the state may conspire against the referendum.

Michael Shepherd

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...