SAN FRANCISCO (Reuters) - A challenge to California’s gay marriage ban failed on Monday to qualify for the 2010 ballot, leaving gay activists mulling a 2012 push and hoping a federal court will overturn the measure before then.

Los Angeles-based Love Honor Cherish carried out a volunteer-driven signature-gathering effort after large groups decided there was not enough time to ensure victory this year, even with some polls showing more than 50 percent support for same-sex marriage.

A 150-day period to gather signatures to place the question on the ballot ended on Monday.

Courts and state legislatures have legalized same-sex marriage in five U.S. states and the District of Columbia, but popular votes have always rejected such unions, which are illegal in the vast majority of U.S. states.

California voters in November 2008 ended a summer of court-allowed gay marriage by enacting a ban on same-sex unions by a 52 to 48 percent vote. The move by the trend-setting state enthused social conservatives and stunned lesbian, gay, bisexual and transgender supporters nationwide.

A San Francisco federal court now is weighing whether the U.S. Constitution prohibits Proposition 8, which defined marriage as a union of a man and a woman. That battle is expected to be appealed up to the U.S. Supreme Court.

“That trial I think is the most import single event in the modern LGBT equality movement,” said Rick Jacobs, head of the Courage Campaign, speaking of the gay and lesbian movement. His community organizing group considered a 2010 push but decided it was too soon.

“If the court rules that Prop 8 is unconstitutional, that is going to catalyze folks on both sides,” he said.

Many gay activists are wary of the Supreme Court bid, fearing conservative justices would not support their cause.

Love Honor Cherish Executive Director John Henning said if voters overturned Proposition 8 in 2012 -- the next time a ballot measure could qualify -- it could effectively take the issue out of the Court’s hands.

“I’d rather repeal Prop 8 than see the Supreme Court review it, given the current composition of the court,” Henning said.