California is set for a major debate on the death penalty following qualification Monday of a November ballot measure that would replace capital punishment with a life term without possibility of parole.

If passed, the measure would make California the 18th state in the nation without a death penalty. During the last five years, four states have replaced the death penalty and Connecticut is soon to follow.

Growing numbers of conservatives in California have joined the effort to repeal the state’s capital punishment law, expressing frustration with its price tag and the rarity of executions. California has executed 13 inmates in 23 years, and prisoners are far more likely to die of old age on death row than by the executioner’s needle.

November’s ballot measure would commute the sentences of more than 700 people on death row to life without possibility of parole, a term that would then become the state’s most severe form of criminal punishment.

Most death row inmates would be returned to the general prison population and be expected to work. Their earnings would go to crime victims.

Backing the new measure are Ron Briggs, who ran the 1978 campaign for a successful ballot initiative that expanded the reach of California’s death penalty; Donald J. Heller, an ex-prosecutor who wrote the 1978 initiative; Jeanne Woodford, a former warden of San Quentin State Prison who oversaw four executions; and former L.A. County Dist. Atty. Gil Garcetti, who said his experience as D.A. helped change his mind about the fairness of the system.

Although their views on the proposition are unknown, former California Chef Justice Ronald M. George and current Chief Tani Cantil-Sakauye, both Republican former prosecutors, have stated publicly that the death penalty system is not working.

The chorus of criticism has death penalty advocates worried, even though California voters have historically favored capital punishment, passing several measures over the last few decades to toughen criminal penalties and expand the number of crimes punishable by death.

“The people of California have regularly voted for the death penalty by wide margins, but of course it has to be a matter of concern,” said Kent Scheidegger, legal director of the Criminal Justice Legal Foundation, which advocates for tough criminal penalties. He said fundraising to defeat the November measure would be difficult.

Scheidegger’s group filed a lawsuit last week seeking a court order to force the state to establish a single-drug lethal injection procedure that his group says should end litigation that has blocked executions for six years.

Fourteen inmates on death row have exhausted their appeals and could be executed if courts permitted the state to go forward, he said. A federal judge who suspended executions cited the possibility that inmates might suffer extreme pain with the three-drug procedure.

A three-year study by a judge and a law professor concluded last year that the death penalty in California costs $183 million more to administer than life without possibility of parole, and that California’s 13 executions cost taxpayers $4 billion. The additional expense includes legal costs for expanded trials and appeals and for housing inmates in single cells.

Scheidegger contended the costs are inflated and cited a 10-year-old report by the state of Indiana that found capital cases there cost 21% more than non-capital murder cases.

Garcetti said he learned as a district attorney that the location where a person was tried significantly affected whether that person would be condemned because of varying attitudes in different jury pools. He called the cost “obscene” and noted that death row inmates in other states have been exonerated.

Given the huge size of California’s death row, “I just feel there is at least one factually innocent person” there, he said.

maura.dolan@latimes.com