SAN FRANCISCO — A group campaigning to put a marijuana legalization measure before California voters said Monday it has enough signatures to qualify for the 2010 ballot.

The measure has far more than the nearly 434,000 signatures needed to make the November 2010 ballot, said Richard Lee, an Oakland medical marijuana entrepreneur and the initiative's main backer.

The proposal would legalize possession of up to one ounce of marijuana for adults 21 and older. Residents could cultivate marijuana gardens up to 25 square feet. City and county governments would determine whether to permit and tax marijuana sales within their boundaries.

The California Secretary of State still must validate the signatures before the measure is placed on the ballot. Campaign organizers say they will submit more than 650,000 signatures next month.

A Field Poll conducted in April found that 56 percent of California residents supported legalizing and taxing marijuana to help bridge the state budget deficit. Still, pro-legalization advocates are divided over whether the ballot measure is being pushed too soon.

Marijuana is illegal under federal law. But some legal scholars have argued the U.S. government could do little to make California enforce the federal ban if the drug became legal under state law.

The measure calls for jail time for anyone who sells or gives marijuana to children. It forbids smoking pot in a public place or in front of minors.