Where does nonprofit activism stop and labor organizing start? It's a question Big Business and President Obama's administration are sparring over now that Big Labor is turning to so-called "worker centers" to revive union organizing.

A recent exchange of letters between House Republicans and the Department of Labor make clear that the administration is going to resist classifying these centers as labor organizations even if they have clear ties to unions.

That will benefit Big Labor because the centers will be able to act without many of the restrictions imposed on labor organizations by federal law. Big Business groups are fuming over what they see as an end-run around the law.

"Worker centers" is a catch-all term for nonprofit organizations that provide union-like services as well as activist groups that engage in activism traditionally associated with unions.

They are distinguished by the fact that the people they represent are typically not unionized. Many unions do, however, back these groups in an effort to reach out to those workers. Such union-backed entities include Working America, the Restaurant Opportunities Center and OUR Walmart.

At its national convention in Los Angeles earlier this month, AFL-CIO delegates approved a resolution aimed at expanding use of these type of organizations. One AFL-CIO document called these non-traditional labor organizations "a key element of a revitalized and successful labor movement."

House Republicans have urged the Labor Department to label these centers as labor organizations.

In an Aug. 26 letter to the House Education and the Workforce Committee, the department's Office of Labor-Management Standards responded by saying, in effect, the centers were not labor organizations because they hadn't yet succeeded in organizing people.

"OLMS found that (the Restaurant Opportunities Center) did not the represent employees as their exclusive bargaining representative, had not signed any collective bargaining agreements or organized employees for such services... There was no evidence ROC existed for these purposes," the letter stated.

That's kind of a Catch-22. DOL is saying federal labor law would kick in only after a company was organized, despite the fact that a major part of the law is to govern how organizing campaigns are done.

In a Sept. 19 letter, Committee Chairman John Kline, R-Minn., responded by scoffing. He noted that ROC's own website states that it has organized "more than 400 workers... and improve[d] workplace policies."

ROC engaged in a 15-month dispute with the Michigan-based Andiamo restaurant chain over labor issues, a fight that ended with a confidential settlement.

"Given these activities, a credible case could be made" that federal labor law ought to apply to ROC, Kline said.