"We're not just protesting," said Brandon Barwick, a 28-year-old student and musician who is the unofficial leader of the sing-along. "We're advocating for a way of governing, a way of living that preserves our freedoms, our rights."
Madison has a long, proud tradition of public protests, from a famous civil rights march in 1969 to violent clashes with police during the Vietnam era. More recently, Walker's law to strip most public employees of their union rights drew massive protests in 2011 and sparked an effort to oust the governor. He survived a recall election in June.
But the Solidarity Singers won't accept defeat. Walker's attack on Wisconsin workers was so severe, Barwick said, that he deserves constant reminders of the damage he caused.
Their efforts might seem puzzling. Protests generally persist only as long as there's a chance to bring change. It can be hard to sustain that energy when there's no clear goal or realistic chance of success.
That's what happened with the Occupy movement, which grew out of anger at Wall Street and a financial system perceived to favor the richest 1 percent. The movement grew too large too quickly for organizers to keep up. Without leaders or specific demands, it eroded into an amorphous protest against everything wrong with the world and eventually fell apart.
State Sen. Fred Risser, the nation's longest-serving state lawmaker, is no stranger to protests. The 85-year-old Democrat, who was first elected in 1956, remembers when a Milwaukee priest and "welfare mothers" took over the state Assembly chamber in 1969 to protest proposed welfare cuts.
The confrontations of the past make him grateful that the Solidarity Singers are nonviolent. But he doubted their singing would make a difference.
"I don't know of any legislators who are changing their views because of that," Risser said. "If their goal is to change the law, that's not going to happen. But I think their goal is to express concern, to have the feeling of participating in peaceful demonstrations."
Walker said the move to limit collective bargaining was necessary to fix the state's $3.6 billion deficit. Democrats took it as a direct assault on unions, one of their core constituencies.
Anywhere from 25 to 50 people - usually a handful of students joined by mostly middle-aged or retired people - still gather every day to sing protest songs for an hour.
Police initially reacted with a hands-off approach, arresting only a handful of belligerent protesters loosely associated with the group. However, the new Capitol police chief has begun cracking down by issuing scores of citations to group leaders, largely for failure to obtain a permit.