SAN FRANCISCO (AP) -- Backers of California's voter-approved ban on same-sex marriages have asked the U.S. Supreme Court to overrule a federal appeals court that struck down the measure as unconstitutional.

Lawyers for the coalition of religious conservative groups that sponsored the ban, known as Proposition 8, petitioned the Supreme Court to review the lower court's finding that the 2008 amendment to the state constitution violated the civil rights of gay and lesbian Californians.

The move, which had been expected since a panel of the 9th U.S. Circuit Court of Appeals issued its 2-1 decision earlier this year, means the bitter, 4-year-old court fight over the ban could soon be resolved.

If the high court declines to take the case, it would clear the way for same-sex marriages to resume in California. Gay couples could get married in the state for several months before Proposition 8 passed, a right the measure specifically was designed to take away. Same-sex couples still have all the rights and benefits of marriages if they register as domestic partners.

The divided appeals court panel cited those conditions, which were unique to California at the time, as grounds for striking down the ban but held that it was not saying any other state bans on gay marriages were inherently unconstitutional. In their petition to the Supreme Court, lawyers for Proposition 8's supporters nonetheless predicted that "The 9th Circuit's error, if left uncorrected, will have widespread and immediate negative consequences."

The Supreme Court is expected to act on the petition this fall.

(Copyright 2012 by The Associated Press. All Rights Reserved.)