Supporters of preventing Washington state from adopting universal background checks for gun sales say they've turned in 340,000 signatures in hopes of qualifying an initiative that would be on the 2014 ballot if not taken up by the Legislature first.

Supporters of Initiative 591 turned in 13 boxes of petitions with signatures Thursday to the secretary of state's office, about six weeks before the Jan. 3 deadline. They can continue to turn in signatures up until the deadline.

I-591 would prevent Washington state from adopting background-check laws stricter than the national standard, which requires the checks for sales by licensed dealers but not for purchases from private sellers. It would also prohibit confiscation of firearms without due process.

The proposal was crafted in response to Initiative 594, also aimed at the 2014 ballot, which seeks to require background checks for all sales.