Summary:Lawmakers in the US state of Michigan have passed a law to limit labour union powers, amid mass protests outside the statehouse.
Republicans, who control the state legislature, have banned a requirement that workers pay union fees as a condition of employment.
The so-called "right-to-work" bill could be signed into law by Michigan Governor Rick Snyder later this week.
Passage of the measure makes Michigan the 24th right-to-work state.
Thousands of protesters were gathered outside the state capitol building in Lansing on Tuesday morning, hours ahead of the final vote on the bill.
One demonstrator, Sharon Mowers, who is a member of United Auto Workers and has worked at General Motors for 13 years, said earlier she was worried the measure would mean lower wages.
"People don't understand the labour movement," she told the Associated Press. "They don't understand the sacrifices people made to get us to this point."
Inside, on the third floor of the capitol, dozens of people circled the rotunda and chanted: "This is our house!" as they waited to get into the public gallery, the Detroit Free Press reported.
Wrangles over right-to-work laws have played out over weeks in some states, but the bill passed in Lansing was introduced only last week.
Proponents say the measure will bring more jobs and economic benefits to Michigan, while opponents say it is designed to weaken unions and will lead to lower wages.
In an interview with a local news outlet on Tuesday, Gov Snyder called the measure "good legislation", adding that it was designed to give workers a choice.
"This is about being pro-worker," he said.
President Barack Obama spoke out on Monday against the law during an appearance in Michigan to discuss a separate matter, his plan to avoid nationwide tax rises and deep spending cuts due to take effect next year.
"These so-called right-to-work laws, they don't have anything to do with economics; they have everything to do with politics," President Obama said.
"What they're really talking about is giving you the right to work for less money."
Opponents of the bill fear the law in Michigan, a bastion of the US labour movement and home to the US car industry, could give the right-to-work movement its biggest boost yet.
Although nearly half of US states have right-to-work laws, Michigan is only the second to pass such a law in the last decade, following Indiana earlier this year.