SACRAMENTO -- A federal judge threatened to put the state's prison system into receivership after warning that a prison guard contract renegotiated by Gov. Arnold Schwarzenegger harms reform efforts in the nation's largest state correctional system.

The California Correctional Peace Officers Association, the guard's union, already has a pattern of interfering with investigations and employee discipline, U.S. District Judge Thelton E. Henderson wrote Monday in a letter received Tuesday by Schwarzenegger.

Schwarzenegger's proposal would worsen problems by granting even more concessions to the union in return for postponing pay increases, despite numerous warnings from a federal court special master, witnesses at Senate hearings, and the governor's own review panel that the union has too much power, the judge said.

Schwarzenegger's administration and the union did not have an immediate comment.

Henderson asked to meet with Schwarzenegger personally to discuss the "continued noncompliance with my remedial orders."

Schwarzenegger wanted the union to give back $300 million in pay raises granted under a controversial labor contract negotiated by former Gov. Gray Davis, but his revised version would save the state only about $108 million over two years.

In return, the revised contract would "give up numerous and important management prerogatives" to the union, undermining reform efforts, Henderson wrote.

"If the State of California is no longer willing to manage the necessary corrective actions, I must consider the appointment of a receiver over the CDC to bring California's correctional system into full compliance with the Court's orders," Henderson wrote.

Henderson said he had been prepared to let Special Master John Hagar work with the new leaders Schwarzenegger appointed to head the Youth and Adult Correctional Agency and the Department of Corrections to fix "systemic problems."

Hagar and Schwarzenegger's review panel both found that "bad investigations, a code of silence and the failure to discipline correctional offices has been condoned for many years by the highest level of California officials," Henderson wrote.