ST. PAUL — A group of state-subsidized personal care assistants is suing over a unionization election scheduled to get underway in Minnesota this week.

The nine homecare providers filed their lawsuit in federal court Monday against state officials, including Gov. Mark Dayton, and the Service Employees International Union. Dayton signed the unionization bill in 2013, and SEIU is backing the organization effort.

The plaintiffs contend the state law violates their right of free political expression and association. They’re asking the court to block the law.

Last month, the U.S. Supreme Court ruled that similar workers in Illinois could not be compelled to pay union dues.

The state Bureau of Mediation Services is set to mail out union election ballots to an estimated 26,000 personal care assistants Friday.