UPDATE 4-New laws will make Michigan 24th 'right-to-work' state
* Approval strikes major blow to organized labor
* Opponents vow to overturn the laws
* Other states watching Michigan closely
LANSING, Mich., Dec 11 (Reuters) - Michigan legislators on Tuesday approved laws that ban mandatory membership in public and private sector unions, dealing a stunning blow to organized labor in the home of the U.S. auto industry.
Republican Governor Rick Snyder was poised to sign the bills into law within days. That would make Michigan the 24th U.S. state with so-called right-to-work laws that prohibit unions from establishing a "closed shop" requiring employees to join unions and contribute dues.
As more than 12,000 unionized workers and supporters protested at the capitol in Lansing, the Republican-dominated House of Representatives gave final approval to the bills. In less than a week, Michigan was transformed from a bastion of union influence to the verge of joining states, mostly in the South, that have weakened legal protections for unions.
While labor leaders decried the legislation, Republican Representative Lisa Lyons said during the debate in the House that the right-to-work laws are not an attack on unions.
"This is the day Michigan freed its workers," she said.
Opponents argue that they undermine a basic union tenet of bargaining collectively with employers for better wages, benefits and working conditions. They also allow workers to opt out of a union, potentially reducing membership.
By weakening unions, Republicans also could hurt the Democratic Party, which traditionally receives a significant portion of its funding and grassroots support from labor unions.
Supporters of right-to-work say some unions have become too rigid and workers should be given a choice of whether to join. They also say that a more flexible labor market encourages businesses to invest and open plants in right-to-work states.
CRIES OF "SHAME"
Right-to-work was approved to cries of "shame" from protesters inside the Capitol building, which was closed to visitors when it reached capacity of 2,200, Michigan State Police Inspector Gene Adamczyk said.
An estimated 10,000 more people demonstrated outside in cold and snowy conditions, including members of the United Auto Workers union, and teachers, who shut down several schools in the state to attend the rally.
A few protesters were ejected from the Capitol after they chanted slogans from the gallery during the debate. Protesters tore down two tents set up for supporters of right-to-work on the grounds of the Capitol but Adamczyk said two people were arrested after scuffling with officers.
The show of force by unionized workers recalled huge rallies in Wisconsin two years ago when Republicans voted to curb public sector unions.
Teamsters union national president, Jim Hoffa Jr., whose father Jimmy Hoffa Sr. was one of the nation's most famous labor leaders and disappeared in 1975 in Michigan, denounced Republican leaders in a speech to the protesters.
"Let me tell the governor and all those elected officials who vote for this shameful, divisive bill - there will be repercussions," Hoffa said. "Some day soon, they will face the voters of Michigan and they will have to explain why they sided with the billionaires to back this destructive legislation."
Unions have accused Snyder of caving in to wealthy Republican business owners who wanted right-to-work passed.
The right-to-work movement has grown in the United States in recent years. Indiana earlier this year became the first state in the industrial Midwest to approve right-to-work and several other states are watching the Michigan action closely.
LEGAL CHALLENGES LOOM
Wisconsin Republicans in 2011 passed laws severely restricting the power of public sector unions. While Wisconsin did not attempt to pass right-to-work, the success of Republicans there in curbing powerful unions such as teachers and state workers encouraged politicians in other states to follow suit.
Republicans in Michigan also were emboldened by the defeat in the November election of a ballot initiative backed by unions that would have enshrined the right to collective bargaining in the state constitution.
Michigan is home of the heavily unionized U.S. auto industry, with some 700 manufacturing plants in the state. The state has the fifth highest percentage of workers who are union members at 17.5 percent. Only New York, Alaska, Hawaii and Washington state are more heavily unionized.
The Detroit area is headquarters for General Motors Co , Ford Motor Co and Chrysler, which is majority owned by Fiat SpA.
The UAW was founded in Michigan after a 1932 protest at a Ford plant in Dearborn left five people dead, increasing public sympathy for industrial workers during the Great Depression and leading to national legislation protecting unions.
Democrats and unions have vowed to challenge the new laws in the courts, to try to overturn them in a ballot initiative and possibly oust some Republicans who voted for right-to-work through recall elections.
Democratic Representative Douglas Geiss said right-to-work laws would lead to a resumption of the protests that led to unions some 70 years ago.
"There will be fights on the shop floor if many workers announce they will not pay union dues," Geiss said.