"Everybody in that room was thinking the same thing — we're going down if we don't repel this," Schaeve said. "It's not about us anymore, it's about the nation, and we're at ground zero."

A spokesman for Walker responded to the strike threat by expressing gratitude for public workers.

"Governor Walker is glad the 300,000-plus good, hard-working public employees are showing up to work to do their job," spokesman Cullen Werwie said.

In a televised address Tuesday night, Walker said 1,500 state employees will be laid off before June 30 if the bill is not passed. Up to another 12,000 public employees — up to 6,000 each from state and local governments — also face layoffs, he said.

Strong probability of a strike

Richard A. Epstein, a professor at the University of Chicago, said he sees a strong probability of a major strike because national labor leaders know that if they lose this battle in Wisconsin, other states will fall.

"They see this as a trillion-dollar proposition if it replicates itself across the country," Epstein said.

Linda Kaboolian, a Harvard lecturer on labor-management issues, said unions are too weak to organize a national strike.