The Wisconsin Senate on Wednesday passed a fast-tracked right-to-work bill with no Democratic support.
The vote in the Assembly was scheduled for next week, and Gov. Scott Walker has said he will sign it into law.
Wednesday's 17-15 vote came after nearly eight hours of debate. Democrats argue right-to-work would be bad for workers, wasn't wanted by businesses and would hurt the state's economy.
Republican supporters maintain the law will give workers the freedom to decide whether to pay union dues and will attract more business to the state.
All Republicans voted for the measure except Sen. Jerry Petrowski, of Marathon. He said he's not convinced it will be beneficial.
Twenty-four states already have enacted right-to-work laws.
Several people were removed from the galleries for disrupting the debate throughout the day. Cullen Werwie, communications director for the Department of Administration, said four arrests were made but declined to discuss details.
Dozens of protesters occupied an area outside the Senate chamber to demonstrate against the bill. They chanted and booed when the Senate took up the issue, but their numbers dwindled from the estimated 2,000 who gathered over the noon hour for a rally to a group that partly filled out the second floor hallway near the chamber.