Supporters of a North Dakota constitutional amendment to limit marriage to heterosexual couples say they have collected more than enough petition signatures for their campaign to put the issue to a November vote.

Only 25,688 signatures are needed to put the amendment on the statewide ballot this fall, but the North Dakota Family Alliance's (search) Web site, which posts updated signature totals daily, said the petition had 38,457 signatures as of 5:40 p.m. Monday.

The petition may have more than 40,000 names by the time it is submitted to Secretary of State Al Jaeger's office on Aug. 3, said Christina Kindel, director of the alliance.

"I never had any anxiety in regards to collecting the signatures," Kindel said Monday. "I have felt very confident since day one that we were going to easily surpass our goal."

Robert Uebel, chairman of Equality North Dakota (search), a gay-rights group that opposes the amendment, said the news was disappointing.

"On the other hand, we also welcome the opportunity to make our case to the people of North Dakota," Uebel said.

Supporters of the amendment have been circulating petitions since early June. The amendment says: "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."

It is intended to block North Dakota recognition of same-sex marriages (search). North Dakota law already bars state recognition of any same-sex marriage performed outside the state, and opponents of the amendment say that makes the amendment unnecessary.

Similar items with be on ballots this summer and fall in Oregon, Arkansas, Georgia, Kentucky, Mississippi, Montana, Oklahoma, Missouri, Louisiana and Utah.

In Michigan, citizen groups opposed to gay marriage have submitted more than the required number of voter signatures to place a proposed amendment on the ballot. The petition is under review by state officials. A petition drive is still under way in Ohio.

In North America, only Massachusetts and some Canadian provinces license gay marriages.