Russ Feingold leapt into the center of the fight for worker rights and people-first budgeting in Wisconsin this week, stirring excitement about the prospect that the popular former US senator might soon be reentering the political fray—as a candidate for an open Senate seat in 2012 or perhaps as the champion of the forces seeking to remove right-wing Governor Scott Walker in a recall election.

Feingold marched with thousands of public- and private-sector workers, farmers and community activists who packed the streets of Madison Monday for a hastily organized march to protests moves by Walker and his allies to enact a state budget that attacks collective-bargaining rights, undermines local democracy and cuts funding for schools and public services.

Though there were plenty of chants of “Feingold for Senate” and “Feingold for Governor,” the former three-term senator went out of his way to steer attention away from his own political prospects and toward challenging the worst excesses of the extremists who now control the statehouse. “I’ve fought a lot of state budget fights in this building,” said Feingold, who served in the state Senate for a decade before his election to the US Senate in 1992. “I’ve never seen anything like this before. I’ve never seen proposals this destructive to Wisconsin’s future and to Wisconsin’s families being seriously considered.”

Feingold has attended a number of the protests at the Wisconsin Capitol since February, when Walker launched his initial attack on collective bargaining rights for state, county and municipal employees and teachers. He has, as well, been an outspoken critic of the governor’s agenda—using media interviews and his activist group, Progressives United, to push back against Walker and his allies. But Monday’s march was the first in which he was front-and-center.

“I’m here to lend my voice to the cause. I know something about budgets. I know how important they are, and I wanted to be here at this critical time to do whatever I can to help the working people that are fighting the Walker budget,” explained Feingold, as he marched with dozens of highway crew workers from Rock County, where he grew up in the city of Janesville. “There really has never been a fight more central, more important, to the working people of Wisconsin. I wanted to stand with the people whose rights are being threatened, to march with them, to say that fighting this governor is the right thing to do and that I am in this fight as a private citizen who is ready to do whatever I can to bring some sense back to this debate.”

Feingold is, indeed, a private citizen. But for Wisconsin Democrats, there is a real desire to see Feingold, a maverick progressive who was defeated in last year’s Republican wave election, jump back into politics. At last weekend’s state Democratic Party convention, a paid of straw polls asked who delegates would like to see run for the US Senate seat that will come open next year and for the governorship in a potential recall election against Walker.

Feingold won both polls by landslides.

So is the former senator thinking of running for senator—or governor? “When people express that kind of confidence in you, you have to take it seriously,” Feingold said of the straw poll results. “It means a lt means a lot to me. These are people I have worked with on campaigns for years, on issue fights. So when they indicate that they’d like to see me run for senator, or for governor, I respect that.”

Still, Feingold, who just finished teaching a constitutional law class and is now deep into writing a book on foreign policy, the lure of the campaign trail is less powerful than some might imagine. There’s no grimace on his face when he refers to himself as a “private citizen”; he likes the title, and the lifestyle.

But he also likes, make that loves, his state.

So Feingold is wrestling with the question of whether to march off the streets and onto the campaign trail. And he is wrestling with the question of whether to return to federal politics or to return to the statehouse where he served as one of Wisconsin’s most engaged legislators in the 1980s and early 1990s. He says he will decide by late summer.

But there are plenty of Wisconsinites who have already decided.

As he led the march around the Capitol Monday, a crowd of firefighters, police offices and county employees was chanting “Recall Walker” in the slow, steady cadence that has become a staple at protests in Madison, Milwaukee, Sheboygan, Superior, Kenosha and communities across the state. A pair of women started chanting “Elect Feingold” in the same cadence. Soon, the “Elect Feingold” chant was echoing around the Capitol Square loud enough to be heard not just by the workers outside but by the legislators—and perhaps even the governor—inside.