Edwards' announcement Thursday is, any way you look at it, more bad news for Sen. Clinton, D-N.Y. It comes the day after two Democratic superdelegates announced they were endorsing Obama, and also the day after three former chairmen of the Securities and Exchange Commission -- one of whom was appointed by Sen. Clinton's own husband, former President Bill Clinton -- also endorsed Sen. Obama, D-Ill.

Even more tellingly, so did the legendary Paul Volcker, the former chairman of the Federal Reserve who laid the foundations for more than a quarter-century of unprecedented prosperity in the United States by breaking the back of inflation under Presidents Jimmy Carter and Ronald Reagan.

Edwards' endorsement, in fact, reflects Obama's greatest political strength -- at least in the short term: his ability to be all things to all men and all women. Volcker is endorsing Obama as a responsible fiscal conservative who may be prepared to bite the bullet and let interest rates soar to prevent a potentially catastrophic collapse of the dollar and stampede of investment capital out of the United States.

But Edwards, although previously a free-trade liberal, reinvented himself in this year's presidential race and ran as an economic populist, championing the virtues of protectionism and restoring America's massively eroded industrial home base.

In theory, therefore, Edwards' endorsement should help Obama significantly in the very area where he remains weakest, by giving him much-needed credentials with the working class, blue-collar voters whom the Democrats must win back to regain the presidency come November.

In reality, however, Edwards' capacity to help Obama, even if he is prepared to campaign for him, appears very limited. For Edwards, while personally an admirable and decent man, and a superficially attractive national political candidate, has never managed to transform himself into a credible political heavyweight. He had to stand down after only a single term in the U.S. Senate from North Carolina because he knew he would have been swept away in his re-election bid. When Sen. John Kerry, D-Mass., picked Edwards -- reluctantly -- as his vice presidential running mate, Edwards proved to have no coattails at all across the South.

Edwards' intimates claimed it was all Kerry's fault, because the senator from Massachusetts ran such an inept, tone-deaf and depressing campaign in 2004, which was certainly true. But when Edwards charged into the primary and caucus battles again this year, he did even worse. Significantly, even though he carefully focused his appeal on low-income, working-class voters whose economic opportunities had shrunk drastically in recent years, he got almost nowhere with them. Clinton, for all the manifold other failings of her campaign, proved more effective at making a connection with them.

Edwards' endorsement of Obama remains highly significant, however. It continues the already far-advanced process in which the liberal Democratic Party establishment is now lining up in its ranks behind the junior senator from Illinois in ways that would do credit to the unity and discipline of a Roman legion.

Clinton, despite her 16 years as one of the party's most eminent standard-bearers, her eight years of clout as a senator from New York and the continued loyal, even impassioned, support of her husband, Bill -- the only Democrat to win two presidential elections since Franklin D. Roosevelt -- has now been frozen out of her own party's mainstream.

Despite Clinton's landslide annihilation of Obama in West Virginia Tuesday -- a state the Democrats simply have to win in November -- she is becoming more marginalized in her own party by the day. Even Ralph Nader would now be more welcome there.

And as to the long-term question as to whether Volcker or Edwards represents the real Obama -- bet on Edwards.