New York City ? Republican vice presidential nominee Sarah Palin says she supports a constitutional amendment banning gay marriage, a break with John McCain, who has said he believes states should be left to define what marriage is.

In an interview with Christian Broadcasting Network, the Alaska governor said she had voted in 1998 for a state amendment banning same sex marriage and hoped to see a federal ban on such unions.

McCain, an Arizona senator, is supporting a ballot initiative in his state this year that would ban gay marriage. But he has consistently opposed a federal marriage amendment, saying it would usurp states’ authority on such matters.