Iowa backers of same-sex marriage warned Wednesday their critics will turn their attention to Iowa after winning a referendum in Maine on Tuesday.

Maine voters rejected a six-month-old gay marriage law, making it the 31st state to do so. Fifty-three percent of the state's voters disapproved.

The vote disappointed gay rights advocates, who hoped the northeastern state might hand them a ballot-box win after courts and governments in three states, including Iowa, had legalized same-sex marriage this year.

"I think it's a very hurtful outcome," said Brad Clark, campaign director for OneIowa, an advocacy group.

Iowa critics of gay marriage, meanwhile, said the result was part of a long line of victories at the ballot box, and they said they'll continue to push state legislators to allow a referendum in Iowa.

"When the people of a state are given the chance to vote, they always support the only definition of marriage - one man and one woman," Bryan English, a spokesman for the Iowa Family Policy Center, said Wednesday.

The Iowa Supreme Court legalized gay marriage earlier this year, and ever since, critics of the decision have pushed state lawmakers to approve a referendum.

Democratic leaders in the Iowa Legislature declined last session to allow a vote on whether to call a referendum. And they've said more recently there are more important issues to deal with next session, including the ailing economy and steep budget cuts.

English said his group will continue to work on rank-and-file legislators to try to force a vote next session.

State Sen. Joe Seng, D-Davenport, said he expected the Maine vote would "energize" gay marriage critics in the state. Seng was among Senate Democrats who refused to sign a discharge petition late in the session to force the referendum question to the floor.

Only Republicans signed it.

Seng said Wednesday he hadn't had time to absorb the Maine result and the effect it might have on what he would do if the discharge petition came up again.

Two consecutive General Assemblies would have to approve a resolution calling for a vote before it could come to a ballot.

Another potential avenue is to call a constitutional convention, an option that will be on the ballot next year.

Clark said OneIowa has sensed building support for gay marriage in the state since the state Supreme Court's ruling.

"I think here in Iowa, people are thoughtful and fair-minded, and they don't want to discriminate against their neighbors," he said.

But English said people ought to have the right to vote.

"We're a state that prizes our process and our liberties," he said. He added there's no reason to think Iowa would vote differently from the way any other state has voted.