Under federal rules, temporary workers assigned to a unionized company are barred from joining a union bargaining unit at the company without the permission of both the company and the staffing agency that sent them. Such consent is rarely granted.

But the National Labor Relations Board may be about to strike down that rule. That would be a cause for great rejoicing among labor unions, which would launch drives to sign up such workers.

Economists say the surge in temporary employment during the past decade has helped push unemployment to rock-bottom levels while helping to dampen wage inflation.

• On any given day, nearly three million Americans work as temps.

• Temporary workers accounted for about 2.2 percent of the nation's work force in 1999, double the 1990 level -- and that percentage is expected to climb even further in coming years.

• More than 70 percent of all temps find permanent jobs within one year, with 29 percent landing the jobs as a direct result of their temporary work assignments.

• Using temporary workers allows companies to quickly and cheaply find new workers, introducing an element of labor-market flexibility.

If unions get their way and the NLRB overturns the so-called Greenhoot rule -- which effectively prohibits union organizing of temporaries -- it would have a chilling effect on many companies' use of temporary workers, employers warn. They say that reducing labor-market flexibility would increase unemployment.

Source: Yochi J. Dreazen, "Regulators Probe U.S. Reliance on Temporary Workers," Wall Street Journal, August 7, 2000.