Mental health employees belonging to the National Union of Healthcare Workers on Wednesday announced they have rescheduled their strike against Kaiser Permanente.

Employees at Kaiser Permanente Behavioral Health in Simi Valley will join 4,000 psychologists, therapists, psychiatric nurses and other health care professionals statewide to strike at Kaiser facilities from Dec. 16 to 20. Roughly 100 Kaiser facilities will potentially be shut down in the state as a result of the strike.

The strike had been set to take place Nov. 11 to 15 but was postponed following the death of Bernard Tyson, chief executive of Kaiser Permanente.

Members of the union are looking for Kaiser to fix a system that they claim leaves patients waiting months for appointments and overwhelms therapists with a “crushing” number of caseloads, the organization said.

Kaiser refuses to negotiate a settlement to avert the strike unless clinicians agree to “significantly poorer retirement and health benefits,” the union added in its statement.

“Mental health has been underserved and overlooked by the Kaiser system for too long,” said Ken Rogers, a Kaiser psychologist. “We’re ready to work with Kaiser to create a new model for mental health care that doesn’t force patients to wait two months for appointments and leave clinicians with unsustainable caseloads. But Kaiser needs to show that it’s committed to fixing its system and treating patients and caregivers fairly.”

“We have been jointly working with an external, neutral mediator to help us reach a collective bargaining agreement,” said Dennis Dabney, vice president of national labor relations and the office of labor management partnership with Kaiser Foundation Health Plan and Hospitals, in a statement. “Last week, the mediator delivered a proposed compromise solution to both sides that we are seriously considering, however, the union has rejected it and announced plans to strike instead of working through the mediated process.”

The mediator’s recommendation, Kaiser said, included wage increases of the following percentages over four years: 3, 2.75, 2.75, and 2.5. Lump sum payments for the second to fourth year include 0.25 percent, 0.25 percent and 0.5 percent, to provide 3 percent increases a year over the terms of the agreement and a $2,600 retroactive bonus.

“Additionally, in terms of retirement, NUHW employees in Southern California have the same defined contribution plan that nearly a dozen other unions have, and that has been in place for more than four years,” continued Dabney in Kaiser’s statement. “Our current proposal on the table actually enriches this program such that a 3-percent employee contribution would have a 9-percent contribution from Kaiser Permanente.”