MINNEAPOLIS (AP) — Members of the Minnesota Nurses Association voted overwhelmingly to authorize a strike against seven health systems in the Twin Cities and Duluth, union officials say.

The vote Monday gave nurse negotiators the ability to call a strike, with a 10-day notice to employers. The union represents 15,000 nurses. The next negotiation session is set for Aug. 30.

Union officials said one of the biggest issues is retention with understaffing contributing to overwork and professional burnout. They said nurses are caring for twice as many patients as normal and that while the conditions existed before the COVID-19 pandemic, they’re worse now.

Union officials say 15 hospitals and would be affected by the strike, including those operated by Allina Health, M Health Fairview, Children’s Hospital, North Memorial and HealthPartners. In Duluth, it’s Essentia and St Luke’s.

Allina Health said it has plans in place to care for patients during any work stoppage, but wasn’t specific.