promised to change politics, and on April 28 the oldest Republican senator put an exclamation on the point by changing parties. Of course, Arlen Specter

‘s changeover was motivated by more than Obama’s “postpartisan” appeal. Specter–a prochoice, pro-civil rights, union-friendly Rockefeller Republican whose vote for the stimulus bill inspired the ire of the right–was all but certain to lose next year’s Pennsylvania primary to a conservative challenger.

The prospect of forced retirement clarifies the mind, and Specter now finds himself “more in line with Democrats.” But which Democrats? If he aligns with mushy centrists, his defection won’t mean much, even if Dems have the sixty votes to avert filibusters. Nowhere is this more evident than with the Employee Free Choice Act

, which Specter and several other Democrats refuse to back. Praise from union leaders for his move suggests that they think he’ll help them forge a compromise. But if Specter’s switch makes an already compromise-prone Democratic caucus more squishy, then he’ll deserve a primary challenge–no matter what the party leaders have promised him. More encouraging is Specter’s professed belief in “the need for Congress and the courts to reassert themselves in our system of checks and balances.” His recent New York Review of Books article reads as if it was written by Russ Feingold

. If Specter changes course on EFCA and fights for civil liberties, he might finish his career where he started–as a liberal Democrat–and his switch could be one of the most important developments of Obama’s first 100 days. Let’s hope.   JOHN NICHOLS

WELCOME TO THE CLUB:

The Nation was a mature 43 years old in 1909, when one of its favorite senators launched La Follette’s Weekly

, a muckraking journal of Midwest radicalism that would eventually become The Progressive

. The immodest goal of Robert La Follette

‘s magazine–which was gathering editors, writers and fans to celebrate its 100th birthday May 1-2 in Madison, Wisconsin–has long been to win “back for the people the complete power over government.” Even if that mission remains incomplete, The Progressive has surely done its part: opposing war and empire; fighting for the New Deal; and advocating for women’s suffrage, justice for Native Americans and civil and gay rights.

The Progressive championed the public’s right to know when editor Erwin Knoll

and writer Howard Morland

successfully challenged the Atomic Energy Act

‘s secrecy clauses; The Nation supported it in that struggle. As clouds again gathered over the Constitution during the Bush era, Progressive editor Matthew Rothschild

defended civil liberties with his meticulous “McCarthyism Watch.” This ongoing crusading is, as our own Victor Navasky

noted in welcoming The Progressive to the circle of 100-year-old magazines, a boon in an era of declining print fortunes. “That’s because they are a cause as much as a business,” says Navasky.