Maine’s largest teachers union is playing a “political game” by endorsing a proposal on November’s ballot to legalize same-sex marriage, Gov. Paul LePage said Friday.

The Maine Education Association’s endorsement is an example of the union’s priorities, focusing on gay marriage rather than expanding opportunities for teacher development, LePage said in a prepared statement.

In a letter Thursday to the union’s president, Chris Galgay, LePage reiterated his previous offer to match, dollar for dollar, any increase in professional development money offered to teachers by the union.

“In Maine, we are blessed with many great teachers,” LePage said in the letter. “Too often, however, union bosses worry about a wide variety of efforts — political campaigns, lobbying, protecting bad teachers, insurances sales, and providing golf and skiing discounts — which are not related to furthering the education of our children.”

The union, which represents more than 24,000 active and retired teachers, voted to endorse the gay marriage proposal on Sunday in Portland during its annual convention of elected leaders from around the state.

It was a unanimous voice vote without debate, said Rob Walker, executive director of the union. He said the vote is consistent with the union’s longstanding support for civil rights.

Walker noted that the union’s constitution calls for the union to stand up for public education and “civil rights for everyone in the state.”

“We are a democracy,” he said. “Our members spoke, and we are going to support it.”

Walker said LePage began telling the union in November that it should focus its efforts on professional development. He said the union does work on professional development but employers are ultimately responsible for funding development programs.

“Making sure we have a highly skilled work force is the job of the employer,” Walker said. “In this case, the people who fund this are the local school districts and the state.”

In 2009, the teachers union opposed the repeal of the same sex marriage law that had been passed by the Legislature. Voters statewide overturned the law, 53 percent to 47 percent.

During that campaign, supporters of the repeal aired television adds saying that children would be taught homosexuality in schools if gay marriage were permitted.

This year, supporters of gay marriage submitted 85,000 verified signatures to put their proposal on the ballot Nov. 6. The law wouldn’t require religious institutions or clergy members to perform same-sex marriage ceremonies.

Maine would be the first state to give same sex partners the right to marry by popular vote. Same sex partners can marry in seven states and the District of Columbia because of court rulings or legislation.