PORTLAND, Maine (Reuters) - Voters in Maine appeared to have overturned a law allowing same-sex marriage enacted by the state's legislature, according to early results of Tuesday's vote gathered by local media.

With 87 percent of precincts reporting, opponents of same-sex marriage led with 52.7 percent of the vote against 47.2 percent, according to unofficial tallies provided by the Bangor Daily News.

A defeat would mark another loss at the ballot box for the movement to allow gays and lesbians to gain certain legal protections available to heterosexual couples.

State lawmakers approved same-sex marriage in May, but the law never took effect as opponents gathered enough support for a statewide "people's veto" referendum.

Connecticut, Iowa, Massachusetts, New Hampshire and Vermont remain the only U.S. states where gay marriage has been approved. In each instance, the laws were enacted by legislatures and judges, not by popular vote.

(Reporting by Ros Krasny, editing by Anthony Boadle)