DOWNEY — Health care employees for Kaiser Permanente are on the verge of striking Monday after the labor contract for 75,000 unionized workers expired.

The union members have voted to authorize a strike to start Wednesday in what is expected to be the largest strike of health care workers in United States history.

"Our patients are not safe and getting the care that they deserve while we're in the staffing crisis," Datosha Williams, a member of SEIU-United Healthcare Workers West, told KTLA. "Us going on strike is us standing up to Kaiser executives to have them fix and address the staffing crisis."

Progress has been made in negotiations, a spokesperson for Kaiser said and urged workers to reject calls for a strike.

The Coalition of Kaiser Permanente Unions warned that workers would strike Wednesday to Friday if a deal was not reached when the unions' current contract expired Saturday.

Dave Regan, president of SEIU-United Healthcare Workers West, said Kaiser has failed to adequately address a staffing crisis that has led to dangerous wait times for patients.

"Kaiser executives refuse to acknowledge how much patient care has deteriorated or how much the frontline health care workforce and patients are suffering because of the Kaiser short-staffing crisis," Regan said in a statement. "The patient care crisis cannot be solved unless Kaiser executives follow the law by bargaining with health care workers in good faith, and take dramatic action now to solve the crisis by investing in its workforce."

Kaiser said its hiring goals this year resulted in more than 9,700 positions filled, "and we are aggressively recruiting to fill more."