Backers of gay marriage say they will take their fight to Oregon’s 2014 ballot, setting up a high-profile political contest on the emotional issue in a state that voted less than a decade ago to constitutionally ban same-sex marriage.

Aya Bentley, 14, of Bellevue, Wash., uses a small bubble-maker as she joins well-wishers in Seattle congratulating gay and lesbian newlyweds in Seattle on Dec. 9, the first day they could marry under the same-sex marriage measure approved by voters last November.

The state’s major gay-rights group, Basic Rights Oregon, made the decision over the weekend to launch a petition drive on Monday to put a measure on the ballot that would allow legal recognition of same-sex marriages. Given the group’s resources and the issue’s high visibility, there is little doubt the group can qualify the measure for the November general election.

“I think people are really coming to understand that marriage is unique and special and you don’t want to deny that to anybody else,” said Jeana Frazzini, executive director of Basic Rights Oregon, after the group’s leaders and advisers met Sunday to finalize their decision to proceed.

Teresa Harke, a spokeswoman for the Oregon Family Council, said her group has been preparing for months to oppose an initiative allowing gays and lesbians to marry. “We have to communicate with voters why it is important to preserve marriage” as being between a man and a woman, said Harke, who predicted that both sides face a difficult fight.

Frazzini said her side received a huge boost after voters in November approved same-sex marriage measures in Washington, Maryland and Maine — marking the first time voters had said that gays and lesbians should be allowed to marry. Nine states and the District of Columbia now recognize same-sex marriages.

Basic Rights Oregon has been laying the groundwork for a statewide vote on the issue since 2009. In 2011, however, the group decided not to go to the ballot in 2012, with Frazzini saying at the time that there wasn’t enough consensus on the issue to have a “reasonable expectation of success.”

But with last year’s landmark victories and a continued shift in the polls toward more public acceptance of gay marriage, Basic Rights officials concluded that they could find fertile ground in 2014.

The most recent public survey on the issue, by Public Policy Polling in December, found that

, while 40 percent were opposed.

Basic Rights Oregon faces an added risk in proceeding in 2014 because it is a non-presidential year when turnout is lower — and the electorate is generally less favorable to liberal causes. For example, after Barack Obama’s initial presidential victory in 2008, turnout dropped in Oregon by nearly 14 percentage points in 2010. And turnout was down more sharply among Democrats than among Republicans.

In addition, Basic Rights Oregon is asking the state’s voters to reverse themselves. In 2004, Oregon voted to constitutionally define marriage as between a man and a woman. The action came after Multnomah County began issuing marriage licenses in March of that year to same-sex couples.

Oregon is one of

on same-sex marriages. Depending on what happens in other states in 2014, Oregon could be the first state where voters jettison a ban they had put in place.

Frazzini said her group would file paperwork Monday morning in the Secretary of State’s office to gather the 1,000 “sponsorship” signatures needed to submit a proposed initiative for preliminary review. The organization then will need to collect 116,284 signatures to actually make the ballot.

She said supporters would begin gathering signatures on Valentine’s Day around the state. The campaign will be run under the name

.

Harke said opponents also already have formed their own campaign organization,

.

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