MINNEAPOLIS — Nearly 5,000 nurses at five Twin Cities hospitals have voted to authorize an indefinite strike amid a dispute over a new contract.

The workers represented by the Minnesota Nurse’s Association voted Thursday to authorize an open-ended walkout at the Allina Health hospitals just two months after a weeklong strike ended without a deal.

Part of the dispute is over health care plans. Allina wants to transition its nurses to the same plan as other employees to save $10 million a year. The corporate plan carries lower premiums but higher deductibles. The nurses want to keep their union plans.

The affected hospitals are Abbott Northwestern and Phillips Eye Institute in Minneapolis, United in St. Paul, Unity in Fridley and Mercy in Coon Rapids.

The union must give a 10-day notice before a strike.