Two Philadelphia-area U.S. Postal Service unions plan protests on Thursday over mail-service counters in Staples Inc. stores.

Postal union leaders say the mail-service counters, to be staffed by Staples employees, threaten higher-wage unionized postal jobs and the survival of traditional post offices. More retail chains could seek mail-service counters, they said.

The protests are part of a "national day of action" by the American Postal Workers Union. Rallies are also planned for Pittsburgh and Easton in Pennsylvania, and Brick Township and Hamilton in New Jersey.

Staples, the office-supplies chain, had no comment.

Postmaster General Patrick Donahoe has said the Staples partnership won't result in job losses at the nation's 33,000 post offices. He said the deal is "all about growing our business."

The union said there is an agreement for postal counters in 82 Staples stores and the number could expand to 1,500 stores.

"We're protesting that the Postal Service and Staples are trying to incorporate postal revenues into Staples stores," Gwen Ivey, one of the local presidents, said Wednesday. She expects 100 to 200 postal workers to protest at the Staples store on the 1500 block of Chestnut Street in Center City between noon and 5 p.m. Thursday.

Vince Tarducci, the second union president, said his local union will protest at the bulk-mail center on Byberry Road in the Northeast.

"If they do it there," Tarducci said, referring to Staples stores, "they will do it in other places."