The plan would require background checks for online sales and private transactions, such as those that occur at gun shows. The checks would be conducted at federally licensed firearm dealers, where people already must undergo such scrutiny before purchasing a new weapon.
Supporters said the measure wouldn't stop all gun violence but would prevent people who shouldn't have guns -criminals and the mentally ill - from easily acquiring them. They contended that the public is ready to push ahead with the idea.
"This issue is gaining traction," said Cheryl Stumbo, who was wounded during the 2006 shooting at the Jewish Federation in Seattle. "We're seeing more and more incidents, more and more deaths, and the public is paying attention."
Washington state lawmakers had considered a similar measure earlier this year, but it didn't pass either the House or the Senate. The initiative does not include some of the exemptions that lawmakers had been considering. For example, law enforcement officers or people who have concealed pistol licenses still would have to go through background checks on private transactions under the initiative.
Zach Silk, a campaign manager with the Washington Alliance for Gun Responsibility, said proponents wanted to ensure that the measure was simple, without a lot of caveats that would prevent the measure from working.
"We wanted to make sure it was the most effective bill," Silk said. The initiative does provide exemptions for transactions between family members, temporary use of a borrowed gun and the purchase of antique or relic guns.
Initiative proponents need to collect about 246,000 valid signatures before Jan. 3 in order to qualify. If it does get enough signatures, lawmakers will have the option of adopting the measure. Otherwise it will be on the ballot in November 2014.
The ballot measure opens a new front in the effort to expand background checks that began in earnest following the December massacre at Sandy Hook Elementary School in Connecticut. While advocates have been successful in some states like Connecticut and Colorado, they have struggled in Congress and other states.
Gun control measures have had mixed results on the ballot. In 1997, Washington voters widely rejected a plan that would have required handgun owners to pass a safety course. After the Columbine High School massacre in 1999 in suburban Denver, voters in Colorado and Oregon approved ballot measures the next year to require background checks for buying weapons at gun shows.
Initiative sponsors believe they have enough support this year. They've raised more than $800,000 already - more than half the amount they expect to need for gathering signatures. Meanwhile, an independent Elway Poll conducted earlier this year found that 79 percent of registered voters in Washington state supported background checks on all gun sales, including private transactions.
A Washington state lobbyist for the National Rifle Association did not immediately return a call seeking comment.