ST. PAUL — A federal lawsuit has been filed over a new Minnesota law that could lead to unionization of certain in-home day care providers.

The lawsuit filed Wednesday pairs with another federal case also seeking to overturn the law. The measure approved last month gives unions authority to press for a unionization vote covering providers who care for children eligible for state subsidies.

The latest lawsuit was filed on behalf of 12 providers and is being paid for by the National Right to Work Legal Defense Foundation. They contend the union drive infringes on freedom of association clauses of the Constitution.

Gov. Mark Dayton said the groups behind the lawsuit are “throwing their little fits trying to throw sand in the machinery and delay” a union election, which he insists is legal.