PLACERVILLE, Calif. — The year was 1978, and the California ballot bristled with initiatives for everything from banning gay teachers to cracking down on indoor smoking. Both lost. But one, Proposition 7, sailed through: expanding the state’s death penalty law to make it among the toughest and most far-reaching in the country.

The campaign was run by Ron Briggs, today a farmer and Republican member of the El Dorado County Board of Supervisors. It was championed by his father, John Briggs, a state senator. And it was written by Donald Heller, a former prosecutor in the New York district attorney’s office who had moved to Sacramento.

Thirty-four years later, another initiative is going on the California ballot, this time to repeal the death penalty and replace it with mandatory life without parole. And two of its biggest advocates are Ron Briggs and Heller, who are trying to reverse what they have come to view as one of the biggest mistakes of their lives.

Partly, they changed their minds for moral reasons. But they also have a political argument to make.

“At the time, we were of the impression that it would do swift justice, that it would get the criminals and murderers through the system quickly and apply them the death penalty,” said Briggs, 54.

“But it’s not working,” he said. “My dad always says, admit the obvious. We started with 300 on death row when we did Prop. 7, and we now have over 720 — and it’s cost us $4 billion. I tell my Republican friends, ‘Close your eyes for a moment. If there was a state program that was costing $185 million a year and only gave the money to lawyers and criminals, what would you do with it?’ ”

California is not the first state to reconsider the death penalty in an era of questions about its morality and effectiveness. And even with these unusual advocates — and a new argument, that the death penalty has cost the state a fortune but produced only 13 executions in 34 years — the repeal faces tough going.

This is a state with a history of colorful crimes and criminals; polls here invariably find strong support for executions. Indeed, the older Briggs says that, unlike his son, his mind remains unchanged.

But Ron Briggs and Heller bring to this campaign a powerful and evocative story: a bid for personal redemption and a call for renewed consideration of the arguments they themselves once made in favor of the death sentence.

“It’s been a colossal failure,” Heller said in his Sacramento office. “The cost of our system of capital punishment is so enormous that any benefit that could be obtained from it — and now I think there’s very little or zero benefit — is so dollar-wasteful that it serves no effective purpose.”

A Field Poll in September found a jump in the number of Californians who would favor life without parole over the death penalty for someone convicted of first-degree murder, to 48 percent last year from 37 percent in 2000. Overall, 68 percent said they supported the death penalty for serious crimes. The report said that keeping inmates in prison for life would cost substantially less than executing them.

Kent Scheidegger, the legal director for the Criminal Justice Legal Foundation, which supports the death penalty, said cost “is probably the only argument that has any chance. The people have heard all the other arguments for years and it has never gotten any traction.”

But he added: “Justice is what we have government for. Why forgo justice for dollars?”