California- Almost 4,000 gay couples, including Rosie O’Donnell and her lesbian partner, learned yesterday that their marriages are null and void.

The California Supreme Court ruled unanimously that the controversial mayor of San Francisco, Gavin Newsom, overstepped his authority by issuing marriage licenses to same-sex couples.

The justices also ruled, 5-2, to nullify the same-sex weddings performed between Feb. 12 and March 11. Those weddings ignited a fierce nationwide debate and prompted President Bush to push for a constitutional amendment to ban same-sex marriages.

“The struggle for civil rights continues in America, as usual,” O’Donnell told the Daily News through a spokeswoman yesterday, adamantly adding: “Vote for John Kerry.”

The court’s rulings yesterday, however, only addressed whether a mayor had the legal authority to go beyond state law. Broader arguments about the legality of gay marriage are expected to be heard before a lower California court next month.

Anti-gay-marriage groups hailed yesterday’s court rulings.

“Instead of helping his cause … Newsom has set back the same-sex marriage agenda and laid the foundation for the pro-marriage movement to once and for all win this battle to preserve traditional marriage,” said Mathew Staver of Campaign for California Families.