Michigan enacted far-reaching legislation Tuesday that threatens to cripple the power of organized labor in a state that was a hub of union might during the heyday of the nation’s industrial dominance.

As thousands of angry union members shouted their opposition outside the state Capitol in Lansing, the Republican-controlled legislature completed work on two measures to ban unions from requiring workers to pay membership dues. Gov. Rick Snyder, a Republican, then signed them into law Tuesday evening.

The “right to work” effort illustrates the power of Republicans to use state legislative majorities won in 2010 to pursue their policy preferences, even after losing a bitter presidential election.

The defeat is devastating for organized labor, which for decades has been waging an uphill battle against declining membership and dwindling influence. But it also strikes at the roots of a Democratic Party that relied on unions for financial support and to marshal voters for President Obama’s reelection.

The new law comes nearly two years after Wisconsin Gov. Scott Walker, a Republican, began a push to curb collective-bargaining rights for public employees. That effort triggered a failed effort to recall Walker.

At the same time, a well-funded campaign to curtail union power swept through several other Republican-controlled states in the industrial Midwest.

Indiana followed Wisconsin and passed laws that limited the reach of organized labor. Lawmakers in Ohio also passed legislation that curtailed collective-bargaining rights of public-sector unions, but voters overturned it.

In crafting Michigan’s measure, supporters avoided some tactical errors from earlier efforts. The measure is attached to an appropriations bill, which exempts it from being taken to a referendum. And it excludes firefighters and police officers, groups that were critical in overturning Ohio’s law.

Proponents call their win in Michigan especially significant because the state is the birthplace of one of the country’s most powerful labor groups, the United Auto Workers. Founded in 1935, the union organized autoworkers, winning wages and benefits that transformed assembly-line work into solid middle-class jobs.

“This is really a message to every other state that is a closed union shop, that if you do it here you can do it everywhere else,” said Scott Hagerstrom, Michigan director of Americans for Prosperity. The group is supported by industrialists Charles and David Koch, billionaires who have pushed for anti-union and other conservative measures.

Supporters predicted that the new law will be a boon to economic growth in an era of global competition. But unions say the measure will starve them of money, weakening their ability to bargain for their members and undercutting their ability to support Democrats, who typically back their causes.

Labor leaders and Democratic state legislators said they had requested that Obama weigh in on the labor fight. They asked the White House to issue a public statement last week declaring the president’s opposition to the legislation, and for him to refer to the labor fight in his remarks Monday during a visit to Redford, Mich.

“You know, these so-called right-to-work laws, they don’t have to do with economics. They have everything to do with politics,” Obama said. “What they’re really talking about is giving you the right to work for less money.”

Labor Department figures show that unionized workers earn more and have better benefits than their non-union counterparts. But the number of American workers who are in labor unions is in sharp decline.

In Michigan, the share of unionized workers has dropped from 28.4 percent to 17.5 percent since 1985. Meanwhile, the nation’s struggle to hold on to manufacturing jobs and the travails of the auto industry made Michigan an economic basket case long before the recession. Unemployment in the state peaked at 14.2 percent and now stands at 9.1 percent, far above the national average.

With increasing numbers of working Americans who must make do with falling wages, frozen pensions and long periods of joblessness, it is unclear whether they consider unions their allies.

The Michigan vote ended a swift change of fortune for the forces of organized labor there. Unions and their supporters spent more than $22 million to back a ballot measure last month that would have guaranteed collective-bargaining rights in the state Constitution, only to see it resoundingly defeated.

 

The rejection emboldened the other side. Sensing an opening, supporters pushed to have the legislature pass the right-to-work measure. Then Snyder, who had previously expressed ambivalence, came out in favor of it.

Greg McNeilly, who heads the Michigan Freedom Fund, a group backed by multimillionaire conservative activist Dick DeVos that spent millions pressing for passage of the legislation, called their success a potentially decisive hit against organized labor.

 

“I think today is their Waterloo,” McNeilly said. “To see the birthplace of forced unionization do a turnabout is a very monumental achievement, and it is historic.”

 

Whatever the impact, union leaders promised to work hard to overturn Tuesday’s actions.

 

“What this means is that for the next two years, we are going to work hard to elect candidates who support the middle class and working class and see what we can do to get this bill turned over,” said Michael Bolton, director of United Steel Workers District 2, which covers Wisconsin and Michigan.