Tennessee voters overwhelmingly approved a constitutional amendment to ban gay marriages Tuesday.

With 75 percent of precincts reporting, the amendment was approved by 1,152,209 voters, or 81 percent, compared to 272,787 votes against, or 19 percent.

The ballot question had to be approved by a supermajority that equals more than half the voters in the gubernatorial election. It was obvious Tuesday that it would clear that hurdle.

State law already defines marriage as the union of one man and one woman, but the amendment should make it safe from court challenge.

The strongest support for the amendment came from married women with children, small-town residents, weekly churchgoers and conservatives, according to an Associated Press exit poll.

Peter Bales, 28, a Nashville resident who considers himself a conservative, said marriage should only be between a man and woman.

"I'd just prefer not to support it or institutionalize those relationships," Bales said. "I think marriage between a man and a woman are better and more healthy for children."

Republican state Sen. David Fowler, who sponsored Tennessee's gay marriage amendment, said he was excited by the results and credited religious groups for getting the ban approved.

"I think it's a signal to the state legislature as well that the people of our state believe in the importance of families. I hope that will carry over in years to come."

Tennessee was one of eight states with gay marriage referendums on Election Day.

South Carolina, Virginia and Wisconsin approved the ban on gay marriage; Arizona, Colorado, Idaho and South Dakota were voting on a similar measure.

Chris Sanders, president of the gay rights group Tennessee Equality Project, said he wasn't pleased with the vote, but the group plans to study districts where the amendment failed and develop a strategy to "advance equality" in the state.

"This is a longterm fight," Sanders said. "We're in this for the long haul. One setback isn't the end of the entire struggle."