Nurses, surgical technicians and other union workers at nonprofit health care provider Kaiser Permanente will vote later this month on whether to authorize a strike as contract negotiations stall.

The health care giant and 26 unions represented by the Coalition of Kaiser Permanente Unions are wrangling over staffing shortages, wages and benefits.

The largest concentration of the group’s 85,000 members work in Southern California, and they have been without a contract since it expired in September 2018.

The threat comes just weeks after the union representing thousands of grocery workers in the region approved a strike.

Neither vote means a strike would be called, but it offers negotiators leverage in talks with employers.

Union officials said the strike could be biggest seen in the United States in decades, and it would hit Southern California particularly hard.

But Kaiser said the two parties are working toward common ground and doesn’t believe it will come to that.

In a statement emailed from a Kaiser spokeswoman, the health care provider’s head of labor relations Dennis Dabney wrote: “We believe we have a framework for resolving negotiations successfully, which will address those areas and also continue to provide market-competitive wages and benefits.”

Kaiser is among the largest employers in Los Angeles, and it operates several hospitals in the region. The vote is slated for July 29.

The Coalition is calling for greater financial transparency, contending Kaiser has moved away from its nonprofit mission.

Manufacturing, retail and trade reporter Rachel Uranga can be reached at [email protected] or (323) 556-8351. Follow her on Twitter @racheluranga.