The endorsement by the California Police Chiefs' Assn. may ease nerves of elected officials from both parties about the plan to save $1.2 billion, which came under fire when details were revealed Tuesday. Critics, including Assembly GOP leader Sam Blakeslee of San Luis Obispo, immediately threatened to oppose the entire agreement to resolve the state's $26.3-billion deficit.

The administration and lawmakers are now discussing whether to delay a vote on the prisons portion of the budget deal. They are hoping to put the package to a vote on Thursday.

But Pasadena Police Chief Bernard Melekian, president of the association, said today that the plan to reduce the inmate population by 27,000, partly by targeting specific offenders who behave well, are sick or have the least time to serve, takes "huge steps in the right direction." He said the plan was far better than an unvarnished early release of inmates that his group had feared would be approved by state leaders.

His eight-member board, which represents 338 chiefs statewide, voted unanimously to support it.

"We think that we've made a lot of progress," Melekian said. "We are very pleased about that, and we anticipate working very closely with them to implement this."

The proposal would allow some inmates with a year left to serve and some elderly and infirm out of prison, but it would keep them on home detention with electronic monitoring. It would also allow inmates to earn more time off their sentences by completing rehabilitation programs, reduce punishment for some lower level crimes and lessen parole supervision for those who demonstrate success out of prison.

The prisons now hold 168,000 inmates.

Soon after news of the plan broke Tuesday, Blakeslee sent his caucus an e-mail with the heading, "Budget Double-Cross? " Blakeslee suggested that he had not known the details and said Republicans would not vote for it.

The budget deal needs a two-thirds vote in each house of the Legislature, so it cannot pass without some Republican support. And with the left and the right of the political spectrum unhappy over different items -- and with many legislators still in the dark about what, exactly, they would be asked to vote on -- the prospects remained uncertain.

Neither the governor's office nor the Legislature had publicly released details of the prison portion of the agreement. When they were revealed, Blakeslee insisted that he had not agreed to them.

He had agreed to a deal including prison cuts, Blakeslee wrote in an apparently hurried e-mail to the GOP caucus, but his understanding was that the details were supposed to be ironed out in August.

"I have called and personally told both Karen and Darrell that their will be no republican votes for any portion of the budget if they allow such a bill to be part of the package," Blakeslee wrote, referring to Senate leader Darrell Steinberg (D-Sacramento) and Assembly Speaker Karen Bass (D-Los Angeles).

By contrast, the Republican leader in the state Senate, Dennis Hollingsworth of Murrieta, said in an interview Tuesday that he continues to support the budget deal.

One possibility would be for Democrats to approve the prison provisions as a separate bill that would require only a majority vote. That, however, would require Republicans to approve the rest of the package knowing that the prison changes would be added.

The governor's corrections chief, Matt Cate, said the administration was doing a "full-court press" to win approval for the plan.

"If we don't achieve these measured, thoughtful, I think smart-on-crime proposals, then we really are in a position where we have nothing left to do but talk about early release," Cate said.

If it passes, the prison plan would amount to a significant reversal of a decades-long pattern of longer sentences and rising prison populations. Steinberg told reporters that the proposal would target the "revolving door" that state prisons have become for lower-level offenders.

The plan resembles recommendations from experts on reducing California's prison overcrowding, which is the focus of a federal lawsuit in which judges have been considering whether to order a mass inmate release.

"We have not done a very good job in California of distinguishing between people who are violent and who belong in prison for a long time, and those who could succeed on the outside with supervision, who have not demonstrated any history of violence," Steinberg said.

The budget plan also would create a sentencing commission to reexamine the state penal code, which would not save money immediately but would advance plans under discussion by lawmakers for years.

The commission would have three years to establish new sentencing guidelines.

michael.rothfeld@ latimes.com