Tens of thousands of Kaiser Permanente workers remained on strike for a second day after negotiators failed to reach an agreement to end a dispute over a short-staffing crisis at health facilities.

A spokesperson for the Coalition of Kaiser Permanente Unions, said that the strike — said to be the largest health-care worker walkout in U.S. history — will continue until Saturday morning at the latest as the group waits for “a meaningful response from Kaiser executives” to its demands.

There are currently no bargaining sessions scheduled with Kaiser, said the spokesperson, Caroline Lucas.

More than 75,000 workers went on strike Wednesday at hundreds of Kaiser Permanente health facilities in California, Colorado, the District of Columbia, Oregon, Virginia and Washington state.

Nearly 60,000 of those workers are in California.

Kaiser Permanente workers in D.C. and Virginia struck for one day and returned to work Thursday, but will continue in the other four states through Saturday morning “barring any dramatic action from Kaiser executives to address the short staffing crisis,” Lucas said.

Operations, chemotherapy treatments and other “non-urgent” procedures were postponed Wednesday due to the strike, NBC News reported.

Kaiser Permanente has said all hospitals and emergency departments will remain open during the work stoppage, but elective procedures may have to be postponed.

Kaiser Permanente is the largest private, nonprofit health-care organization in the U.S.

It serves nearly 13 million patients and operates 39 hospitals and more than 600 medical offices across eight states and D.C.