Despite same-sex couples winning the right to marry in Massachusetts some six months ago, opponents have struck back - voters in 11 states across the United States on Tuesday approved constitutional amendments limiting marriage to one man and one woman.

The states of Arkansas, Georgia, Kentucky, Michigan, Mississippi, Montana, North Dakota, Oklahoma, Ohio, Utah and Oregon overwhelmingly approved constitutional amendments that deny legal status to homosexual couples looking to tie the knot.

Oregon showed the most modest support — 56 percent with two-thirds of precincts reporting — for the amendment. In the other 10 states, the amendments passed by solid margins, ranging from 60 percent in Michigan to 86 percent in Mississippi.

Although gay-rights activists who campaigned vigorously hoped to prevail in the state Oregon where the measure, considered the broadest of the 11 because it barred any legal status that "intends to approximate marriage," gathered equal support from men and women, blacks and whites.

According to reports, gay-rights activists in Georgia, Ohio and Mississippi were considering court challenges of the newly approved amendments.

Gay rights activists vowed to challenge some of the amendments in court.

"Basic human rights should not be put up for a popular vote," said Matt Foreman, executive director of the National Gay and Lesbian Task Force.

"We're confident that the Bill of Rights is going to secure the freedom to marry for gay Americans."

None of the 11 states allow gay marriage now, though officials in Portland, Oregon, married more than 3,000 same-sex couples last year before a judge halted the practice.

Earlier this year, Massachusetts' highest court ordered the state to grant marriage licenses to gays. San Francisco Mayor Gavin Newsom defied a voter-passed state law banning gay marriage - Proposition 22 - and allowed thousands of gays to marry in his city. The state Supreme Court later invalidated more than 4,000 of these marriage licenses.

A 1996 federal law already defines marriage as between a man and a woman. And all the states with ballot measures, except Oregon, have laws outlawing gay marriage, as do 27 other states. The eastern state of Vermont, however, allows civil unions.

President George Bush and other opponents of same-sex marriage, however, say a federal constitutional amendment is needed to prevent what they call "activist" judges from overturning the 1996 law.