PORTLAND, Maine (November 3, 2009)--Early returns Tuesday night showed a tight contest in Maine's closely watched referendum on whether to uphold or repeal a law allowing same-sex marriage.

The law at stake was passed by the Maine Legislature in May but never took effect because of a petition drive by conservatives.

A vote to uphold the law would mark the first time that the electorate in any state endorsed gay marriage, which could energize activists nationwide and blunt conservative claims that same-sex marriage is being foisted on states by judges or lawmakers over the will of the public.

However, repeal would be another heartbreaking defeat for the marriage-equality movement, following the vote against gay marriage in California a year ago.