A coalition of unions representing thousands of Kaiser Permanente health care workers warned they will walk off the job again next month if a deal is not reached with their employer.

Facilities across California, Washington, Oregon, Virginia and Washington DC have threatened to strike for a second time if a new labor contract is not agreed before November 1, after a contract for 3,000 more Kaiser employees in Seattle expires on October 31.

The second planned strike would involve more employees and it would be longer than the first, running from November 1 through November 8, according to a statement by the coalition.

"For months, Kaiser executives failed to listen to the feedback from frontline healthcare workers about the need for executives to follow the law in negotiations and about the impacts that the Kaiser short staffing is having on patients," Caroline Lucas, the executive director of the Coalition of Kaiser Permanente Unions, said in a statement.

The first strike began on October 4 and ended on October 7 after an employment contract for 75,000 Kaiser workers expired without a new agreement.

Spanning multiple states, it was the first national strike effort at Kaiser Permanente and the largest health care worker strike in US history. Patients told CNN they were unable to make appointments or had care postponed in light of the October strike.

The coalition has argued that Kaiser Permanente, one of the largest nonprofit health care providers in the United States, has not gone far enough in its promises to address a shortage of staffing, which the coalition has called "unsafe."

Kaiser has said it promised union representatives that it would aggressively hire new employees. Kaiser said it has already hired 10,000 workers for union-represented roles so far in 2023.

The coalition also said outsourcing had emerged as a major sticking point in negotiations.

Kaiser executives have "refused to agree to common sense limitations on subcontracting and outsourcing, which keep experienced healthcare workers in jobs and provide strong continuity of care for patients," the coalition said.

In a statement, Vincent Staupe, a spokesperson for Kaiser Permanente, said the health care organization has received notice from the unions of the potential strike.

"We are scheduled to return to the bargaining table on October 12 and Kaiser Permanente remains committed to reaching an agreement that is good for our employees, our members, and our organization, and we will continue to bargain in good faith with the Coalition," Staupe said.