If a proposition on the ballot passes, life in prison without parole would become the harshest punishment in the state.
The ballot measure would also convert the death sentences of 725 inmates to life-in-prison terms.
A federal judge halted executions in California in 2006, saying the state's lethal injection protocol amounted to cruel and unusual punishment.
Voters reinstated the death penalty in 1978. Thirteen inmates have been executed since then.
Backers of the measure say abolishing the death penalty will save the state millions of dollars through layoffs of prosecutors and defense attorneys who handle death penalty cases, as well as savings from not having to maintain the nation's largest death row at San Quentin State Prison.
Opponents of the measure, such as former Sacramento U.S Attorney McGregor Scott, argue that lawyers filing "frivolous appeals" are the problem, not the death penalty law.
The Associated Press contributed to this report.