A group plans to wage a petition campaign for a North Dakota constitutional amendment to define marriage as the union of a man and woman.

Supporters of the move turned in a proposed amendment to Secretary of State Al Jaeger on Wednesday. He has until June 7 to review the ballot measure and approve it for circulation.

Massachusetts began licensing same-sex marriages earlier this month. Opponents of homosexual marriage have expressed fears that states which have not sanctioned the practice will be legally forced to accept marriages performed elsewhere.

Christina Kindel, director of the North Dakota Family Alliance, is chairwoman of the initiative campaign. The alliance promotes socially conservative beliefs. It supports tax cuts for families and opposes abortion and gambling, according to policy statements posted on its Web site.

Kindel campaigned against the North Dakota introduction of the Powerball lottery, which voters approved in November 2002. She could not be reached immediately for comment.

Sherri Paxon, of Mandan, a co-chairwoman of Equality North Dakota, a gay rights organization, called the proposal sad and unnecessary.

"There are many states attempting to do this," Paxon said. "I think it's sad when any state or the federal government writes discrimination into the constitution."

Activists in at least six states are circulating petitions to put same-sex marriage constitutional amendments on the ballot. In at least six others, state legislatures have scheduled November votes on the issue.

North Dakota's Constitution allows residents to bypass the Legislature and put constitutional amendments and state laws to a vote. A ballot measure's supporters must gather a specified number of petition signatures to put a proposal on the ballot.

Supporters of the marriage amendment must gather signatures from at least 25,688 eligible North Dakota voters. The required number represents 4 percent of North Dakota's population, as counted by the 2000 federal census.

The petitions must be turned in by Aug. 3 for the measure to be placed on the November general election ballot.

The proposal would add two sentences to Article 11 of the North Dakota Constitution. They read: "Marriage consists only of the legal union between a man and a woman. No other domestic union, however denominated, may be recognized as a marriage, or given the same or substantially equivalent legal effect."

Along with prohibiting same-sex marriages, the amendment also would apparently bar civil unions of homosexual couples, which are allowed in California and Vermont. Civil unions give gay couples many of the same rights as heterosexual married couples.

In 1997, the North Dakota Legislature approved a law barring state recognition of same-sex marriages. The proposed ballot measure seeks to go a step further, and add similar language to the state constitution.

Paxon, who was formerly known as Sherri Parsons, married her spouse, Vickie Paxon, last August in British Columbia. In Canada, the provinces of British Columbia, Ontario and Quebec now allow same-sex marriage.

Paxon said the North Dakota law has prevented her marriage from being recognized in her home state.

"It already does what this constitutional amendment would propose," she said. "It seems to me to make it even doubly discriminatory because we already have a law on the books that says marriage is between a man and a woman. I think you're adding insult to injury by writing a constitutional amendment."

Congress and a number of other states are debating proposals to ban same-sex marriages. The U.S. Senate and House are considering identical proposed amendments to the U.S. Constitution. President Bush has endorsed the concept of a federal constitutional amendment to prevent recognition of homosexual marriages.