LEWISTON, Maine — Supporters of same-sex marriage officially kicked off their efforts to get the issue on the 2012 ballot Thursday morning with a news conference outside Lewiston City Hall.

“We have been going door to door, talking to them and hearing their journey toward support. In two separate polls, conducted over the last five months, 53 percent of Mainers surveyed said they support letting gay and lesbian couples marry here. People are changing their minds on this issue,” said Betsy Smith, executive director of EqualityMaine. “We intend to finish the job we started in 2009.”

The issue was intensely political when it dominated Maine news in 2009. A bill allowing same-sex marriage passed largely along party lines in the Democrat-controlled Senate and House that year and was signed into law by Democratic Gov. John Baldacci.

A people’s veto effort was immediately launched, run by a coalition of evangelical Christian churches and the Catholic church in Maine. Outside support was provided to both sides and overall spending on the referendum question totaled $9.6 million.

The side opposed to same-sex marriage had the support of the National Organization for Marriage and spent roughly $3.8 million compared to the $5.8 million spent by supporters of gay marriage in the “No on 1” campaign.

The people’s veto was successful and the same-sex marriage law was overturned 300,848 to 267,828.

This time around, gay marriage supporters must get 57,277 signatures to get the question on the November 2012 ballot. They hope to build on momentum in Rhode Island and in New York, which earlier this month became the sixth state to allow gay marriage.

Smith said Thursday that she fully expected opponents of same-sex marriage “to come at us hard, to raise money.”

The Rev. Bob Emrich, pastor of Emmanuel Bible Baptist Church in Plymouth and one of the leaders in the last campaign veto the law, on Thursday disputed the notion that more Mainers now support same-sex marriage.

“I don’t believe opinion has shifted at all. I think if anything people are more resolved to say ‘leave marriage alone, the definition is what it is,’” said Emrich. “The resistance to this is there, it’s very real. It’s too early to say what form it will take for sure — but I think it will be a broader coalition than it was last time.”

Marc Mutty, director of the office of public affairs for the Portland Diocese of the Catholic Church, put out a statement Thursday, saying the church would continue to support traditional marriage, and that “what role it will take in any type of public campaign” remains to be determined.

“We are greatly disappointed to hear of EqualityMaine’s plan to launch yet another referendum campaign on the issue of same-sex marriage in Maine. The people of this state rejected same-sex marriage in November of 2009 and should not be put through what will likely be another divisive drawn-out campaign,” Mutty said. “The people of this country have rejected same-sex marriage in all cases where the issue has been put on the ballot; there is no reason why we should expect a different outcome this time.”

Only two states have had statewide votes on the same-sex marriage issue, Maine and California. In both cases, opponents of gay marriage prevailed. Same-sex marriage has become legal in New York, New Hampshire, Vermont, Massachusetts, Connecticut, Iowa and in Washington, D.C.

Smith said supporters of same-sex marriage have continued talking to the public about the issue, working to change the overall public sentiment. Supporters chose Lewiston to kick off the drive because in 2005, city voters supported the Maine Won’t Discriminate campaign, which outlawed discrimination based on sexual orientation in areas including employment and housing. In 2009, however, Lewiston was one of the few major metropolitan areas in the state where voters did not support same-sex marriage.

Smith said she believed the city’s voters were thoughtful and reasonable, and the difference in votes showed more conversations needed to be had to illustrate same-sex marriage as an issue of equality.

Smith said two polls done in the last five months surveyed roughly 1,400 members, and had margins of error of between 3 percent and 4 percent. The polls showed 53 percent supporting same-sex marriage, but Smith noted that they were just snapshots in time. Indeed, in the lead-up to the 2009 vote, same-sex supporters had polls showing them winning the referendum.

Organizers also enjoyed the support of Lewiston Mayor Laurent Gilbert, a Catholic who said he believes everyone should treat others the way they want to be treated.

“I understand that there are many fair-minded people in Maine who are truly grappling with this issue,” said Gilbert, according to a transcript of his speech. “They believe all people should be treated fairly, but are conflicted about what they were brought up to believe.”

Another speaker Thursday was Pastor Michael Gray of the United Methodist Church in Old Orchard Beach.

Gray said he was active in the campaign to support same-sex marriage in 2009. He had held a traditional view of marriage in the past, but that changed over time, Gray said.

Gray on Thursday submitted the proposed referendum question to the Secretary of State’s office, asking voters “Do you favor a law allowing marriage licenses for same-sex couples that protects religious freedom by ensuring no religion or clergy be required to perform such a marriage in violation of their religious beliefs?”

Having his name on the referendum petition meant little to him personally or professionally, said Gray.

“It means nothing to me — I’m not putting anything on the line at all,” he said, noting that his congregation was largely supportive of same-sex marriage. “But it means everything to my LGBT friends and neighbors. I’m doing it for them.”