The opening of Postal Service retail centers in dozens of Staples stores around the country is being met with threats of protests and boycotts by the agency's unions.

The new outlets are staffed by Staples employees, not postal workers, and labor officials say that move replaces good-paying union jobs with low-wage, nonunion workers.

"It's a direct assault on our jobs and on public postal services," said Mark Dimondstein, president of the 200,000-member American Postal Workers Union.

The dispute comes as the financially struggling Postal Service continues to form partnerships with private companies, and looks to cut costs and boost revenues. The deal with Staples began as a pilot program in November at 84 stores in California, Georgia, Massachusetts and Pennsylvania as a way make it easier for customers to buy stamps, send packages or use Priority and certified mail.

Union leaders fear that if the Staples program is successful, the Postal Service will want to expand it to more than 1,500 of the company's other stores. That could siphon work and customers away from nearby brick-and-mortar post offices, taking jobs from postal workers and even leading traditional post offices to close.

The union says it's not asking to shut down the program. It wants the counters to be run by postal employees, not workers hired by Staples. The average postal clerk earns about $25 an hour, according to the union, plus a generous package of health and retirement benefits. The Staples post office counters are run by nonunion workers often making little more than the minimum wage.

Last month I wrote about an attempt by the International Association of Machinists and Aerospace Workers to unionize technical workers at an Amazon.com Inc. warehouse in Delaware. This was my take back then: "I don't think it's an exaggeration to say that if unions manage to make substantial inroads at Amazon, it will be the greatest advance that the labor movement has experienced in decades."

Well, on Wednesday night, workers voted to reject the union. So far, the citadel of the new economy remains unbreached. The vote wasn't even close: 21 to 6.