INDIANAPOLIS—Public support appears to be waning and opposition growing for an amendment to the Indiana constitution banning same-sex marriage, according to a recent statewide poll.

The Indianapolis Star-WTHR poll found 49 percent supported such a constitutional amendment, down from 56 percent in a March 2005 survey, while those opposing one rose to 44 percent from 40 percent in the earlier survey.

A proposed amendment would have to win approval from the Indiana Legislature in the upcoming session next year before it could go before voters in November.

The poll results heartened Jon Keep, president of Indiana Equality, a GLBT advocacy group that has lobbied against the amendment.

“I think a lot of it has to do with people realizing that this may not be the most important issue in the state right now,” Keep said.

The amendment has given rise to concerns that it might impede recruitment efforts by major employers by jeopardizing domestic partner benefits some of them offer. Opponents also have argued the amendment could deny unmarried heterosexual couples protection under domestic violence laws.