A group opposing Question 1 on Tuesday’s ballot is citing an incident at Gorham Middle School last month to make its case in the referendum on legalizing same-sex marriage in Maine.

On Saturday, three days before the vote, Protect Marriage Maine issued a news release with an online link to a “shocking news report” about a presentation given during Gorham Middle School’s “Diversity Day” program Oct. 25.

The discussion, led by Proud Rainbow Youth of Southern Maine, a program of Maine Mental Health Partners’ Community Counseling Center, was supposed to be about tolerance.

During a question-and-answer session after the presentation, the subject of sex came up.

The ensuing discussion prompted a letter of apology from the school’s principal to parents.

Protect Marriage Maine said the incident supports its argument that homosexuality will be taught in Maine schools if Question 1 passes, allowing gay couples to wed.

Mainers United for Marriage, the main group advocating for passage of Question 1, said the subject was inappropriate but had nothing to do with same-sex marriage. It said opponents are using the incident as a last-ditch scare tactic to sway the vote.

The incident came at the end of three hours of presentations on tolerance. The topics included cliques and autism, as well as sexual identity, said Principal Robert Riley.

Proud Rainbow Youth of Southern Maine made three presentations to groups of students that morning. The third presentation, delivered by adults to about 25 eighth-graders, ended with a question-and-answer session, Riley said.

When no students asked any questions, he said, the presenter asked if they had learned about safe gay sex in their sex education classes.

Riley wouldn’t give details of what the presenter said then, but said “it was not within the scope of the day.”

Kristy Howard, the mother of an eighth-grader who was in the class, said the presenter talked about foreplay and using plastic wrap as a substitute if a condom wasn’t available.

Riley, who was told about the discussion by a teacher, said he sent a letter home with all middle-school students on Oct. 29 apologizing for the incident.

The letter did not describe the incident in detail, characterizing it only as a discussion of “topics that we do not deem appropriate for our middle school.”

Mary Jane Krebs, president and chief executive officer of Community Counseling, responded to questions about the presentation with a prepared statement Monday saying that the center and the youth program “are looking into all concerns raised and will address them.”

She did not respond to specific questions about the qualifications of the presenter or the details of what was said.

Carroll Conley, co-chairman of Protect Marriage Maine, said Monday that the incident proves that some same-sex marriage advocates don’t believe parents have the right to be notified or to remove their children from school if a controversial topic is being taught.

“If (Maine schools) are willing to teach our kids how to engage in foreplay, do you really think they won’t force gay marriage instruction of young children when it is the law of the land?” said a news release issued Saturday by Bob Emrich, the group’s other co-chairman.

In 2009, when Mainers voted to overturn a gay-marriage law that the Legislature had passed, opponents made a similar argument.

But in a recent interview, David Connerty-Marin, spokesman for the Maine Department of Education, said, “Regardless of what happens with Question 1, nothing changes, which is that local schools decide curriculum.”

Administrators of public school systems based in Brunswick, Lewiston, Oxford County, Portland and Augusta say nothing would change in their districts because they don’t teach marriage.

David Farmer, communications director for Mainers United for Marriage, said the incident in Gorham was inappropriate but the principal handled it properly.

He called the argument by Protect Marriage Maine “more lies from the campaign that’s trying to deny loving, committed couples in Maine” the right to get married.

Farmer said what’s taught in schools has nothing to do with deciding who should be able to get a marriage license.

“They are pushing this story out at the last minute in desperation,” he said.

As a result of the incident, Gorham Middle School will have more in-depth discussions with outside groups about what they’re presenting to students, Riley said, and with teachers about how to handle conversations that stray into something inappropriate.

The middle school may request permission slips for students to participate in certain conversations, he said. “We’re going to put some safeguards in place to make sure we protect our students.”

Riley said he has received a few phone calls from parents, but has received more emails from people who do not have children at the school.

Howard, who asked her son for more details about the incident after reading Riley’s letter, said she contacted WCSH-TV to ensure that parents knew what had happened.

Howard said she trusts the middle school will make changes to ensure that nothing similar happens, but the incident has turned her against legalizing same-sex marriage because she’s concerned about how it could affect school curriculum.

Howard said she feels the topics discussed during Diversity Day “should be taught at home.”

Riley said that if he had thought his school’s Diversity Day discussion would turn into political fodder, he would not have scheduled the program right before the election.

“Our agenda is not to be political,” he said.