MINNEAPOLIS (WCCO) — Thousands of Minneapolis nurses are entering their fourth day of a week-long strike.

On Tuesday, the Nurses’ Association called on Minnesota’s attorney general to audit the finances of Allina hospitals.

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The union says Allina will reportedly spend more than $25 million to bring in replacement nurses for the strike.

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That’s more than the $10 million a year Allina says it will save if nurses switch to a high-deductible health insurance plan. Allina’s CEO said it’s the same kind of health insurance the union recently accepted at a Duluth hospital.

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The nurses say the strike will continue for the next four days.