Restore Equality 2010 chairman Sean Bohac says the volunteer-run group fell short of gathering the nearly 695,000 signatures needed to put the initiative before voters. Monday was the deadline for submitting the signatures to the Secretary of State's Office.
Bohac says Restore Equality's failed effort was undermined by the decision of more established gay rights groups not to participate in the campaign.
He says same-sex marriage supporters now are turning their attention to trying to repeal Proposition 8 in 2012.
A lawsuit to overturn Prop. 8 also is pending before a federal trial judge.