Continued from page 1

Labor backers predicted that the Wisconsin rallies, when protesters stormed the legislative chambers, clashed with police and defaced the Capitol, could be repeated throughout the nation. At least seven other states have moved forward with their own Wisconsin-style proposals.

The Rev. Jesse Jackson, who led a prayer before the Assembly session Thursday, told Fox News that the backlash could get ugly unless union-breaking Republicans capitulate.

“So they’re going to escalate the protests — you will either have collective bargaining through a vehicle called collective bargaining or you’re going to have it through the streets,” said Mr. Jackson. “People here will fight back because they think their cause is moral and they have nowhere else to go.”

Organizers called for public school students nationwide to walk out of class Friday afternoon in a show of support for Wisconsin teachers. Liberal filmmaker Michael Moore announced the walkout Wednesday on MSNBC-TV’s “The Rachel Maddow Show.”

“This is war. This is class war,” Mr. Moore said.

Conservatives countered that the televised reports of angry pro-union mobs would have the opposite effect of increasing support for curbs on collective bargaining.

“I think governors will be emboldened. I think the public employees unions have been a weight around their necks for too long, and this is their chance,” said Steve Gunn, a spokesman for the Education Action Group in Michigan, which advocates public school reform.

The measure is expected to be challenged in court over the legality of the Senate vote. In the absence of Democratic senators, Republicans removed spending provisions from the bill, making it a collective-bargaining measure instead of a fiscal bill that would have required a 20-member quorum before a vote.

Critics also insisted that not enough notice was given for the conference committee meeting in which Republicans carved up the bill. The Senate chief clerk later released a statement saying the rules allow no advance notice for meetings when the chamber is in special session.

Analysts predicted the bill could wind up in limbo if a judge issues an injunction preventing the measure from taking effect until legal issues are resolved.

This article is based in part on wire service reports.