Opponents of California's gay marriage ban, Proposition 8, have been cleared to begin collecting signatures for a measure that would repeal the constitutional amendment, the AP reported.

The Los Angeles-based gay rights group Love Honor Cherish must collect 807,615 valid voter signatures by May 14 to quality for the November 2012 ballot.

Voters narrowly approved Proposition 8 in 2008, five months after the California Supreme Court legalized gay marriage. Roughly 18,000 gay and lesbian couples married during the brief period of time that such unions were legal.

“This is severely impacting people, loving couples who cannot get married. It has severely impacted me not being able to get married,” said Tom Watson, board chair of Love Honor Cherish. “It's been more than three years since Prop 8, and a majority of California residents have realized that it is a mistake to deny loving same-sex couples the right to marry and are ready to reverse the mistake that was made at the ballot box. We should give them that opportunity.”

Love Honor Cherish announced it would back the effort after Equality California, the state's largest gay rights advocate, declined to do so. Equality California cited divided support for marriage equality in the state, the economy and an ongoing legal challenge to the law in explaining its decision.

The 9th U.S. Circuit Court of Appeals in San Francisco is expected to rule shortly on a lower court's decision that struck down Proposition 8 as unconstitutional. Final arguments in the appeal were heard earlier this month.