SACRAMENTO, Calif. — California regulators for the second time Monday rejected a proposed new method of carrying out the death penalty by lethal injection, another move that slows the process for California to resume executing death row inmates.

A voter-backed initiative aimed at speeding up executions, though, may render the regulators’ decision moot.

The Office of Administrative Law did not elaborate in its three-paragraph decision rejecting the rules. But officials previously said the proposal wasn’t clear on how the execution team would be selected and trained; how the drugs would be obtained and administered; and how a condemned inmate should be treated in the days and hours before the execution.

Those issues were raised during the first rejection in December.

California has nearly 750 inmates on death row, but only 13 have been executed since 1978, the last in 2006. Since then, death penalty foes and supporters have engaged in a push-pull over when and how to resume executions, if at all.

One of those fights is over the method of executing inmates.

State and federal judges have barred the old method of using a series of three drugs, prompting the need for new rules.

The regulations up for approval Monday would have allowed condemned inmates to be executed using one of two powerful barbiturates. Inmates could also choose the gas chamber.

Kent Scheidegger, legal director of the Criminal Justice Legal Foundation, which sued to force the new rules, thinks it shouldn’t be necessary for regulators to consider the latest proposal.

He said the regulations must be approved by state and federal judges.

“This is stupid,” he said. “This additional layer of bureaucracy is completely unnecessary.”

The state Supreme Court in August upheld Proposition 66 ending the requirement that prison officials receive approval from state regulators. Death penalty opponents asked the judges to reconsider it with a Nov. 22 deadline, but Scheidegger expects the justices to uphold their earlier ruling.

If so, Monday’s regulatory rejection won’t add much delay, he said.

Department of Corrections and Rehabilitation spokeswoman Terry Thornton said the state will continue following the regulatory process while waiting to see what the justices decide.

If the high court ruling stands, the next step would be for state officials to ask a federal judge and a Marin County Superior Court judge to lift separate injunctions that blocked California’s old way of executing inmates using a combination of three lethal drugs.

Critics have complained that Democratic office-holders have delayed the rules for years because they are in no rush to resume executions.

The latest rejection shows the proposed rules remain “deeply flawed on many levels and is further evidence that California is in no position to resume executions,” Ana Zamora, the American Civil Liberties Union’s criminal justice policy director, said in an email.