"The challenge is finding people or a group of people willing to put up the funds, who want to see it get done in 2014, not wait till 2016," said Berton Duzy, California Cannabis Hemp Initiative.
Duzy figures it will take about a $1 million to gather valid signatures from 504,000 registered voters.
A study by the state's legislative analyst says the initiative could save the state $100 million per year in law enforcement and court costs.
Supporters say decriminalizing it would reduce the prison population as well.
"The idea of legalizing is to stop locking people up for using pot and to eliminate the black market and the cartels from selling pot," said Duzy.
But opponents worry legalizing marijuana would create more teen and adult addicts.
A statement from Citizens Against Legalizing Marijuana says: "There is so much wrong with this measure people should not even sign the petition. Marijuana is a dangerous drug causing physical, emotional, and mental harms for many."
Supporters of the initiative say they are on a tight schedule: They need to gather the signatures by August 18 to place it on the November ballot.