By John Cranford, CQ Columnist

What can it possibly mean that three former chairmen of the Securities and Exchange Commission, two of them Republicans, have endorsed the presidential bid of Barack Obama ?

Considering the news came last week on the same day that former candidate John Edwards handed his support to Obama with great fanfare, it’s no surprise that the announcement from a trio of former regulators landed with a quiet thud. After all, hardly any ordinary American has ever heard of William Donaldson, Arthur Levitt or David S. Ruder — or has a clue what they stand for.

Still, it’s quite possible that the vast majority of corporate executives, Wall Street denizens and investors (an increasingly large part of the population) know more than a little about these men. And what is known is that each of them leaned hard against the anti-regulatory wind when they were charged with overseeing U.S. financial markets.

In a brief statement released May 14 by the Obama campaign (and leaked to The Wall Street Journal a day earlier), the three former SEC chairmen said the United States faces “monumental economic challenges” and they believe the Democratic senator from Illinois “can provide the positive leadership and judgment needed to take us to a stronger and more secure economic future.”

That was plainly intended to resonate with the majority of Americans who have indicated that economic concerns are at the top of their list in this campaign. And without saying so directly, the praise for Obama was a clear slap at Republican contender John McCain , who until recently was as willing as President Bush to embrace his own general lack of economic knowledge and to scratch his head whenever questions about the economy arose.

Former Federal Reserve Chairman Paul A. Volcker added considerable heft to the endorsement from the ex-regulators by signing onto their statement, though he already had thrown his support to Obama in January. But the timing of the announcement seemed curious, coming as it did before Obama has locked up the Democratic nomination and being overtaken by Edwards’ telegenic embrace of Obama at a Michigan rally.

Then again, not one of the four signers of this economic endorsement is particularly known for playing the PR game. They’ve always been mostly about substance and unafraid of controversy.

Donaldson, a Bush family friend named by the current president to bring order and credibility to the SEC after a particularly bad patch, wound up quitting two years later under fire from the U.S. Chamber of Commerce because he took seriously the job of cleaning up after a spate of corporate scandals and putting the Sarbanes-Oxley corporate accounting law into force.

Levitt, who was appointed by Bill Clinton and was the longest-serving chairman in SEC history, always has been blunt-spoken. He challenged the orthodoxy of Wall Street and, among other things, forced changes in the cozy relationship between corporate chieftains and stock analysts that often left ordinary investors in the dark.

And Ruder, tapped for the agency by Ronald Reagan at the end of his second term and seen at first as a caretaker, took on the established view of passive regulation and particularly targeted the little-understood world of derivatives trading after the stock market crash of 1987.

Then, there’s Volcker, picked for the Fed by Jimmy Carter and reappointed by Reagan, who ignored calls for Volcker’s head after the central bank tightened credit in the early 1980s and wrung inflation out of the economy to such an extent that it’s just now rearing its head for the first time in decades.

No Gimmicks

All four are generally regarded as guardians of the interests of individuals and the economy generally. None is seen as a toady to special pleadings. All have long pedigrees: Donaldson ran his own Wall Street firm, the New York Stock Exchange and Aetna Inc. Levitt ran the American Stock Exchange and the New York City Economic Development Corp. Ruder was dean of the Northwestern University School of Law, where he remains a professor emeritus. At 81, Volcker is constantly on call as a consultant and troubleshooter.