The nationwide debate over gay marriage (search) reached the ballot box in 11 states Tuesday as nearly one-fifth of America's voters had a chance to decide whether their state constitutions should be amended to deny marriage rights to same-sex couples.

Most, if not all, of the bans were expected to win overwhelming approval. However, national and local gay-rights groups campaigned vigorously in Oregon (search), where polls showed a close race, and in a few other states to try to prevent a sweep.

None of the 11 states allows gay marriage now, though officials in Portland, Ore., married more than 3,000 same-sex couples last year before a judge halted the practice. Supporters of the amendments contend the measures are needed as an extra guard against state court rulings like the one in Massachusetts (search) a year ago that legalized same-sex marriage there.

The proposed amendments in Mississippi, Montana and Oregon refer only to marriage, specifying that it should be limited to unions of one man and one woman. The measures in Arkansas, Georgia, Kentucky, Michigan, North Dakota, Ohio, Oklahoma and Utah would ban civil unions as well.

In most cases, those additional provisions generated extra controversy. Some prominent Republican politicians and GOP-leaning newspapers, while stressing that they opposed gay marriage, spoke out against the amendments on grounds that the measures might prevent the extension of even very limited partnership rights to unmarried gay and straight couples.

In five of the states, legislators placed the proposed amendments on the ballots, while in the six others — Arkansas, Michigan, Montana, North Dakota, Ohio and Oregon — the measures were advanced by conservative, church-backed citizens groups that collected signatures on petitions.

Many gay-rights activists and their allies depicted some of the petition drives as a divisive, GOP-backed tactic to boost conservative turnout on Election Day in crucial battleground states like Ohio and Michigan.

Already this year, voters in Missouri and Louisiana have weighed in on the issue, with gay-marriage-ban amendments winning more than 70 percent of the vote in both states.

Louisiana's amendment was later struck down in state court on the ground that it improperly dealt with more than one subject by banning not only same-sex marriage but also any legal recognition of common-law relationships, domestic partnerships and civil unions.

Even if all 11 amendments were approved, the debate would rage on. Conservatives say they will continue to press for a federal constitutional amendment banning gay marriage, on the premise that even toughly worded bans in state constitutions could be overturned by the U.S. Supreme Court.

Gay-rights activists, meanwhile, will continue pressing marriage-rights lawsuits in states like Oregon, California and New Jersey, where they believe the high courts might eventually rule in their favor.

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