OLYMPIA — The long-running political brawl between labor unions and the state's home-builder association could be headed for a battle royal.

The Building Industry Association of Washington (BIAW), one of the state's most powerful conservative voices, is considering sponsoring a so-called "right-to-work" initiative that would prohibit mandatory union dues. Any such effort is certain to face strong opposition from state and national union groups.

"It would clearly be the most divisive campaign that we've seen in this state in many years," said Dick Davis, president of the business-backed Washington Research Council.

Washington is one of 28 states where unions can negotiate agreements that require all employees who benefit from a contract to pay dues or representation fees.

Rick Bender says unions would "come out in force."

Business leaders and many of their Republican allies have long complained that mandatory dues violate individual workers' rights and give unions unfair advantages in the workplace and in politics.

However, in a state where unions wield enormous clout, right-to-work advocates haven't been willing to press the issue. But Tom McCabe, the BIAW's outspoken executive vice president, said the homebuilder association's board of directors is seriously considering pushing a right-to-work initiative or some other measure aimed at reducing labor's influence.

McCabe said the group wants to do something dramatic to retaliate against recent efforts in the Democrat-controlled Legislature that would have taken a multimillion-dollar bite out of the association and removed much of its political clout. The legislation, which appears dead for this year, was pushed hard by the Washington State Labor Council.

"They've thrown down the gantlet, and we have to respond," McCabe said.

Some business leaders say they would support a BIAW push for a right-to-work measure. But others worry that it could backfire and invigorate the state's labor movement.

Labor Council President Rick Bender is all but daring McCabe to follow through on his threat.

"He can do whatever he wants," Bender said. But if a right-to-work measure makes it to the ballot, he said, union members would "come out in force" to defeat it. Bender said other union-backed candidates and causes would reap the benefits.

McCabe said the BIAW's polling indicates there would be strong support for a right-to-work effort. He said the group is looking at a few other options, such as an initiative that would require unions to get permission every year from each member before using any of that employee's dues for political spending.

McCabe said he isn't sure exactly when the group would try to get an initiative on the ballot, but said it probably wouldn't be this fall.

Over the past 50 years, 22 states have adopted right-to-work laws. The last two were Idaho in 1986 and Oklahoma in 2001.

Supporters of the effort in Oklahoma argued it would drive down business costs and "liberate" the state's economy. Since the measure passed, union membership in Oklahoma has fallen dramatically.

Unions paint right-to-work efforts as union-busting and say the ultimate result is lower pay and reduced benefits for workers.

They also point out that, in contract talks, mandatory-dues clauses — also known as "union-security agreements" — have to be approved by workers and the employers.

Carolyn Logue, who heads the state chapter of the National Federation of Independent Business, said a vast majority of her 15,000 members would support a right-to-work ballot measure.

"It's not right for employees to be forced into a union," Logue said.

But Bender said he doubts any of the state's biggest employers would get involved.

"If employees knew that their company was supporting right-to-work, it would cause serious discontent," Bender said. "Because what you've done there is basically declare war on the workers."

The Association of Washington Business (AWB), which represents most of the state's largest businesses, is often at odds with labor. But the association would be very wary about supporting a right-to-work effort, said Don Brunell, the group's president.

"We would be really, really careful about something like that," he said.

Former Seattle Mayor Wes Uhlman, a member of the AWB's board, said there's good reason to be cautious.

Uhlman got his start in politics in the late 1950s, the last time there was a big right-to-work push in Washington state. Uhlman said the issue made it to the ballot twice during that time and was soundly defeated. He said the campaigns sparked a huge union uprising and helped Democrats make big gains in the Legislature.

Ralph Thomas: 360-943-9882 or rthomas@seattletimes.com