MADISON, WIS. - The battle raging inside the Capitol here is not just for Wisconsin anymore.

Busloads of union supporters from other states are descending on the building's grounds, carrying signs and denouncing proposed legislation that isn't even directly about them.

On the opposite side, Tea Party ralliers picked up signs of their own over the weekend and national groups are urging nationwide support for Wisconsin Gov. Scott Walker's efforts in an online petition campaign called "Stand With Walker," and calls for local rallies and vigils Wednesday.

As the unrest in Madison continues into its second week, national forces are converging at the scene of a volatile duel between fiscally conservative government leaders and powerful public employee unions. Similar struggles are erupting around the country: In Indiana, House Democrats took a page from their Wisconsin counterparts' playbook and walked out of session Tuesday to block a Republican bill against mandatory union dues.

Nationally, the debate seems to be gaining momentum.

"The stakes are very, very high," said Ronald Greene, associate professor who specializes in political communication at the University of Minnesota. "When the right of collective bargaining becomes the issue, this is an all-or-nothing issue for everyone concerned."

In an address Tuesday night, Walker, a Republican, praised state residents for the passionate, but largely civil, debate so far. "I pray, however, that this civility will continue as people pour into our state from all across America," he said.

Earlier Tuesday, security around the Capitol tightened as the Wisconsin Legislature reconvened. The stalemate continued, still missing 14 Senate Democrats who fled the state preventing the Senate from taking up the controversial bill that would curb union negotiating power. As the state Assembly started to debate the bill Tuesday morning, Democrats began to introduce what they promised would be "hundreds" of amendments.

Labor leaders said they would agree to monetary cuts, but don't want curbs on their collective bargaining rights. Walker and many GOP lawmakers have refused that compromise.

Turning up the pressure, Walker warned that state employees could start receiving layoff notices as early as next week if the bill isn't passed soon and debt refinancing is stalled. Existing union contracts could forestall the layoffs for weeks or months.

Events elsewhere

In Ohio, a similar debate drew thousands of union protesters Tuesday, prompting officials there to lock the doors to the Statehouse. Earlier, Walker had advised Ohio Gov. John Kasich: "Don't blink."

Dozens of rallies to support Wisconsin workers have been scheduled around the country this week. Protesters marched in Las Vegas on Monday and in Boston and St. Paul on Tuesday.

More than 1,000 Minnesota union workers raised their arms and voices at the Capitol to declare their solidarity with unions in Wisconsin, chanting "We are one." Gov. Mark Dayton assured the cheering crowd that "drastic extreme measures will not become law here. ... We will not become Wisconsin."

Republicans control the Minnesota House and Senate but Dayton, a DFLer and union supporter, said he would not abide GOP moves to curtail workers' rights. While Minnesota Republicans have introduced measures to eliminate collective bargaining deadlines, eliminate pension contributions, cut the state workforce and freeze state workers' pay, Dayton has made clear his veto pen is ready.

Choosing sides

Others traveled to Wisconsin to support their allies.

Around the Wisconsin Capitol's rotunda and halls, protest signs offer "Solidarity from Boston" and "Michigan supports WI workers." Supporters from New York and Chicago signed posters taped to the Capitol walls.

And Jesse Jackson greeted Madison students who returned to school Tuesday after four days of canceled classes.

Three busloads of Minnesota union laborers also marched here Tuesday.

St. Paul Public Works employee William Peterson plowed snow on the streets of St. Paul until 4 a.m. Tuesday, he said. One quick shower and a four-hour bus ride later, he stood bundled on the Wisconsin Capitol lawn.

Tim Mackey, business manager for the Minneapolis Laborers' local union, said Minnesota workers came to Madison because "this is ground zero for the fight right now ... If it's allowed to happen here, it's going to run across the country."

That's exactly the hope of the Virginia-based nonprofit Americans for Prosperity, promoters of the "Stand With Walker" campaign. "Every state should adopt Governor Scott Walker's common sense reforms," said the electronic petition at www.standwithwalker.com, whose signature count stood at 66,000 and counting Tuesday night. The group's website also gives a flavor of its efforts with a photo gallery of their protesters and signs, one of which used the University of Wisconsin "W" emblem to say "Walkin' With Walker."

Americans for Prosperity was founded with the help of conservative activist David Koch, executive vice president for Koch Industries Inc. and a major contributor to Walker's campaign.

"The bottom line," said AFP President Tim Phillips, "is that collective bargaining is being used to force extravagant pension and health benefits that are crippling state budgets like Wisconsin's."

The Associated Press and staff writers Richard Meryhew and Rachel E. Stassen-Berger contributed to this report.

Pam Louwagie • 612-673-7102