MADISON, Wis. (AP) — Republican legislators plan to intervene in a new lawsuit challenging restrictions on public workers’ unions.

GOP lawmakers passed a law known as Act 10 in 2011 that stripped almost all public workers of their collective bargaining rights.

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Two chapters of the International Union of Operating Engineers filed a federal lawsuit May 3 in Milwaukee alleging the act violates free speech guarantees. The lawsuit names Democratic Attorney Josh Kaul as a defendant, noting he’s responsible for enforcing Wisconsin law.

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Republicans don’t trust Kaul to represent their interests in court. Senate Majority Leader Scott Fitzgerald said in a news release Monday that Republican legislative leaders will seek to join the lawsuit so they can defend the law.

Kaul spokeswoman Gillian Drummond didn’t immediately respond to an email.

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