PHOENIX — The Arizona Senate voted Friday night to ask voters in November to amend the state constitution to define marriage as a union between one man and one woman.

The measure was defeated earlier this week, but supporters were able to bring it to another vote. It had previously been approved by the House.

Supporters say the proposal would protect the sanctity of families by helping to prevent judges from overturning a state law that already prohibits same-sex marriages.

Opponents say the proposal is unnecessary and that its backers are pandering to social conservatives in an election year.

In 2006, Arizona voters rejected a state constitutional amendment that would have banned same-sex marriage and stopped government from recognizing civil unions of same-sax couples.