Kevin Johnson

USA TODAY

In the only state that took its gun policy debate to the ballot box this week, Washington voters easily approved a measure to expand background checks to cover all private sales and transfers of firearms.

The $11 million effort, whose supporters included Bill and Melinda Gates, bested a competing proposal and made Washington the fifth state to approve expanded checks since the massacre at a Connecticut elementary school in 2012.

Largely overshadowed by the GOP's capture of the Senate, the Washington vote is being touted by gun control advocates as a potential template for establishing universal background checks as a condition of all gun sales throughout the country.

"It's a game changer,'' said Dan Gross, president of the Brady Campaign to Prevent Gun Violence. "While we'll never take our eyes off the prize of federal legislation, the result in Washington shows us that we can have a huge impact in the short term.''

Last year, the push to enshrine universal background checks in federal legislation for all gun transactions failed as part of a package offered by the Obama administration in the aftermath of the Sandy Hook Elementary School shooting that left 20 children and six educators dead.

Federal law requires background checks for those purchases made at federally licensed gun dealers, which prohibit sales to those with criminal records or the mentally ill. Private sales, online transactions, gun show exchanges and other transfers do not require such checks.

The Brady group and other gun control advocates have long contended that the unregulated transactions, including private sales, represent a potentially dangerous loophole that allows firearms to flow to the otherwise prohibited. Gun rights groups assert that additional checks only further restrict arms rights.

Unsuccessful in past attempts to pass gun check legislation in Washington, a coalition of gun control advocates, which included backing from former New York mayor Michael Bloomberg's firearm control groups, took the issue directly to voters as part of a ballot initiative, ultimately capturing about 60% of the vote Tuesday.

"Washington, D.C., failed to take action, so the people of Washington state took matters into their own hands, and the results are clear: Voters support common-sense measures to prevent gun violence," Bloomberg adviser Howard Wolfson said in a statement after the vote. "If elected leaders won't change the laws that make it too easy for dangerous people to get guns, Americans will change their elected officials — or they'll take the issue to the ballot."

Cheryl Stumbo, the citizen sponsor of the Washington measure known as I-594, hoped the victory would prompt other states to do the same.

"We're hoping that this can roll through state by state,'' she said.

Similar campaigns may follow in Nevada and Oregon.

National Rifle Association spokesman Andrew Arulanandam said such a strategy would not go unchallenged.

"We'll be there to fight it,'' Arulanandam said, adding that the issue in Washington state has not been settled.

"All options are on the table,'' he said, referring to a possible legal challenge or possible legislation that would override the initiative. "Wherever this goes, we will fight it.''

Dudley Brown, president of the National Association for Gun Rights, said advocates are bracing for new attempts to expand gun checks at the ballot box.

"There is no question that they will be trying to push these by (voter) initiatives,'' Brown said. "We think it gives you absolutely nothing. It is a means of surrender in advance of the fight.''