SAN FRANCISCO – Backers of California’s ban on same-sex marriages asked the U.S. Supreme Court on Tuesday to overrule a federal appeals court that struck down the measure as unconstitutional, a move that means the bitter, four-year court fight about Proposition 8 could soon be resolved.

Lawyers for the coalition of religious conservative groups that sponsored the voter-approved ban 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 request had been expected since a panel of the 9th U.S. Circuit Court of Appeals issued its 2-1 decision earlier this year.

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 was designed to take away.

Same-sex couples still have the rights and benefits of marriage controlled by state law 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 as a violation of the U.S. Constitution’s promise of equal protection. But it also went out of its way to state it was not saying similar bans in six other states it oversees 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 decision “will force states to make an all-or-nothing choice: either to retain the traditional definition of marriage without any recognition of same-sex relationships or to radically redefine – with no possibility of reconsideration – an age-old institution that continues to play a vital role in our society today,” they said.

“The 9th Circuit’s sweeping dismissal of the important societal interests served by the traditional definition of marriage is tantamount to a judicial death sentence for traditional marriage laws throughout the Circuit.”

Lawyers for two same-sex couples who first challenged Proposition 8 in 2009 said they would urge the Supreme Court to reject the case. The high court is expected to act on the petition this fall.

Justices also have been asked to review a series of challenges to the federal Defense of Marriage Act, which prohibits the federal government from recognizing same-sex unions and thereby prevents gay couples who are legally married from filing joint income tax, receiving Social Security survivor benefits or securing other national benefits of marriage.