“If they succeed in Wisconsin, the birthplace of A.F.S.C.M.E., they will be emboldened to attack workers’ rights in every state,” Mr. McEntee said. “Instead of trying to work with public employees at the bargaining table, they’ve decided to throw away the table.”

On paper, Wisconsin might seem an unlikely candidate for an assault on unions. Like many other states, it has grappled with large spending gaps during the economic downturn, but its projected deficits for the next two years are nowhere near the worst in the country  more like in the middle of the pack.

Its 7.5 percent unemployment rate is below the national average. Its pension fund is considered one of the healthiest in the nation, and it is not suffering from the huge shortfalls that other states are facing.

Those facts have groups on both sides thinking if it can happen there, it can anywhere.

In Columbus, Ohio, Tea Party organizers said they had 300 to 500 people turn out on Thursday for a counterdemonstration against several thousand union members.

“We weren’t well-versed in everything about the bill and why they’re doing what they’re doing except that we’re broke as a state,” said Adriana Inman, an organizer with the Fairfield Tea Party in Southwest Ohio, who attended the rally. She said that her group had many union members.

Some union members who are trying to preserve their rights have been cheered by what they have seen in Wisconsin.

Joe Rugola, executive director of the Ohio Association of Public School Employees and an international vice president of A.F.S.C.M.E., said that 4,000 protesters gathered at the Columbus Statehouse on Thursday to preserve union rights. “Yesterday at the Statehouse, everyone was talking about the images they had seen in Wisconsin, and it gave them great heart and made folks determined to equal that effort.”