The polls suggested he could be elected to an open US Senate seat or that he could beat Wisconsin Governor Scott Walker in a recall election. And there were more than a few activists on the national scene who entertained the less likely dream that he might make a presidential bid as a progressive reformer.

But former US Senator Russ Feingold has chosen another political role for 2012: citizen.

In an e-mail that supporters in Wisconsin and across the country will receive Friday morning, Feingold writes: “I have decided not to run for public office during 2012.”

“This was a difficult decision, as I thoroughly enjoyed my tenure in both the State Senate and the U.S. Senate, and I know that progressives are eager to reverse some of the outrageous policies being pursued by corporate interests at both the state and federal levels. I am also well aware that I have a very strong standing in the polls should I choose to run again for the U.S. Senate or in a recall election for governor,” says the former three-term senator who was defeated in the “Republican wave” election but then quickly rebounded to become a popular prospect for the marquee races of next year: as the Democratic nominee to fill the seat that will be vacated by US Senator Herb Kohl, D-Wisconsin, or the party’s candidate in an effort to oust the controversial governor. “After twenty-eight continuous years as an elected official, however, I have found the past eight months to be an opportunity to look at things from a different perspective.”

Feingold’s decision marks the end of speculation about his potential candidacies—for now, as he says in his e-mail: “I may seek elective office again someday.” But it also sets off a rush by other candidates, including Congresswoman Tammy Baldwin, D-Madison, an all-but-announced contender for the Senate seat, as well as other prospects such as Congressman Ron Kind, D-LaCrosse, and former Congressman Steve Kagen, D-Appleton. Republicans, such as former Governor Tommy Thompson, who has been organizing a Senate run, will also feel more relaxed about running now that Feingold says he is out. (In polling Feingold was the consistent leader in match-ups, even with widely-known and personally-popular Thompson, who the former senator led 48-47 in the most recent Public Policy Survey.)

Among those talked about as potential gubernatorial candidates are Milwaukee Mayor Tom Barrett, outgoing Senator Kohl, former Dane County Executive Kathleen Falk, state Senator Jon Erpenbach and several other legislators who rose to prominence during the intense debate over Walker’s move to strip public employees of most collective bargaining rights.

Feingold thought seriously about both contests, especially during a recent sojourn on northern Wisconsin’s Madeline Island, where he withdrew from public pressure to think and write.

The former senator, who is deep into the writing of a book on foreign policy, has also accepted a full-time teaching schedule this fall at Milwaukee’s Marquette School of Law, where he taught courses that focused on constitutional concerns in the spring. The book, While America Sleeps, with its conscious title reference to the Winston Churchill’s classic 1938 essay, While England Slept (and to a young John Kennedy’s Why England Slept), is a serious consideration of foreign policy missteps over the past decade. Its publication will see Feingold, a longtime member of the Senate Foreign Relations Committee and a frequent critic of US military policies, re-enter the international-policy debate.

Feingold says he will use the book launch to make appearances in Wisconsin and across the country to raise concerns about what happens “when too many political operatives in the nation try to shift the political discourse away from the fundamental national security and international issues that will determine our futures and those of our children and grandchildren.”

Feingold will also maintain his citizen-activism as head of the reform group Progressives United, which he founded after leaving the Senate.

This pattern of activity—teaching, writing, speaking out and organizing for reform—was the one Feingold set for himself after the 2010 election. He readily acknowledges that two developments, Kohl’s decision to step down and battles that arose over Governor Walker’s policies, forced a rethink. Feingold joined demonstrations against the Walker agenda and campaigned and was an outspoken backer of efforts to recall Republican state senators who sided with the governor.

“The one thing many of us did not anticipate at the outset of this year was the extreme assault on the working families of Wisconsin in particular and the nation as a whole,” said Feingold, who raised money for and campaigned on behalf of Democratic candidates who defeated two Republican state senators in recent recall elections and for Democrats who beat back recall challenges. “I was happy with some of the results of this year’s Wisconsin state senate recall elections, and was glad to be able to play a small role in supporting all of the Democratic candidates,” notes Feingold.

That last comment serves as a reminder that, even if he is not planning to run for anything in 2012, Feingold retains the political “bug” that he caught as a kid campaigning with his father—a Progressive Party activist turned Democrat—in southern Wisconsin’s Rock County.

Thus, even as he steps back from next year’s contests, the former senator is outlining his own political schedule—that of the politically engaged citizen activist—for 2012. Despite his differences with President Obama on a host of issues, Feingold makes it clear he is a supporter of the Democratic incumbent. But as always, he will be looking beyond candidates and parties and toward issues and ideology—particularly the passion for political reform that animated his almost three-decades long career in elected office.

“When I said on election night last year that it ‘was on to 2012,’ I meant it. As I said those words I was especially thinking of the need to re-elect President Obama. I will be working to re-elect him and hope to play a significant role in that effort,” explains Feingold.

“But,” he adds, “since the aggressive tactics of Governor Walker and the legislature ensued, those words now also mean retaking the state government from these corporate-backed operatives is a special priority. The entire political climate is more infected by the domination of very wealthy individual and corporate interests than perhaps at any time in our nation’s history. That is why I founded Progressives United, an organization devoted not only to overturning the Citizens United decision but to challenging those involved in the political process who, for short-term political gain, are willing to seek and accept unlimited corporate contributions. This practice should be strongly opposed regardless of party and regardless of whether I otherwise support these candidates. In many ways, this is the overriding political struggle of our time. It is more important than whether or when one person runs for office again. That is why, at this time, I am devoting my primary political energy to this cause and this organization.”

And, of course, he is leaving his options open with that “while I may seek elective office again someday” line.