Two top Republicans on the House Education and Workforce Committee recently demanded a Labor Department investigation into union political activity on Social Security. The stated reason for this interest by the panel's chairman, John Boehner of Ohio, and the head of its subcommittee on employer-employee relations, Sam Johnson of Texas, is that organized labor's persistent protests against the Bush plan raise questions about whether laws have been broken.

"The debate over how to ensure the solvency of Social Security for future generations should be open and honest," Boehner said in calling on the Bush administration to launch an investigation. "But it shouldn't be influenced by special interests who may be breaking federal law."

Nor should it be influenced by special interests that may be using their political clout to exact revenge in the form of a taxpayer-financed investigation. Might this explain the lawmakers' attack on the AFL-CIO? Organized labor, you see, is enjoying a rare moment of success.

Through its public protests and vigorous lobbying, it has managed to get some big investment firms to back out of business coalitions that provide financial and lobbying support for the White House Social Security effort. The firms manage billions in union pension assets.

And, one by one, they've been deciding that their union business is a plump bird in hand compared with the uncertainty of a deal on Social Security promoted by Bush.

The Financial Services Forum, an umbrella organization for executives of large financial services companies, pulled out of Compass, a business group that's been supporting the president's plan. The forum joins Waddell & Reed Financial Inc. and Edward D. Jones & Co. in abandoning business lobby groups. More big-name money houses are under pressure to follow.

Curiously, Boehner and Johnson targeted the unions for investigation days after the Financial Services Forum pullout became public. And they sought an inquiry into one issue: whether labor pressure on financial firms breaches the "fiduciary duty" that union pension funds owe to beneficiaries. That issue has been promoted by Derrick A. Max, a top lobbyist for the business groups that are losing members because of the union effort.

Max, the executive director of Compass and leader of the business-backed Alliance for Worker Retirement Security, also is a former Republican staff member of the Education and Workforce Committee. During a recent train ride to Washington, I overheard him discussing with companions a plan to find sympathetic union members who might file complaints charging that the unions had breached their "fiduciary duty" to choose fund managers solely for financial reasons. Now members of Congress have done the deed instead.

In a phone interview several days later in which I asked him about his conversations on the train, Max told me he had contacted Bush administration officials, whom he declined to name, to press his theory that union lobbying of Wall Street firms that hold their pension assets is a breach of pension trustees' duty. "I've been arguing to anyone who would listen," Max says. Nonetheless, he says he did not contact anyone on the Education and Workforce Committee. A committee spokesman said Boehner had acted on the basis of media reports about the union activity.

The AFL-CIO says that the congressional complaints are not valid.

One charge - that its sidewalk protests on the Social Security issue may violate a long-standing ban on "secondary" picketing - doesn't apply because the prohibition involves picketing during job actions, not public policy disputes. The other - the claim that urging Wall Street to abandon the pro-privatization lobby breaches a "fiduciary duty" - doesn't apply to the AFL-CIO because the labor federation runs no pension fund. Only individual unions have such funds.

"The only thing that's illegal is the effort to coerce the Labor Department to suppress labor's First Amendment rights," says Damon Silvers, the AFL-CIO associate general counsel.

Maybe there's been some dark plot by organized labor to bring Wall Street to its knees and harm its own members' pensions in the process.

Or maybe this is just what it seems to be: a union lobbying campaign that has so far turned out to be more effective than the one business mounted. In the logic of Washington, it's payback time - with public resources used for the retaliatory hit.