The American Postal Workers Union is calling on congressional leaders to stop planned changes at Scarborough's mail distribution center.
The Union says it's been working with management for months, hoping to stop the transfer of equipment from Scarborough to a facility in Nashua, New Hampshire.
The proposal could go into effect as early as this weekend.
Union leaders say the move will lower delivery standards across southern Maine, potentially slowing service.
"If they walk into a local post office and they want to send a parcel and their option, say, is First Class mail which is traditionally two days. Why would we be successful in up selling through Priority mail, which is a better service with the tracking and the guarantee when it's still two day service? They're receiving no benefit." Says Scott Adams, of the Local 458 American Postal Workers Union.
U.S. Senator King sent a letter to the USPS Postmaster General, voicing his concern regarding the proposal to scale back operations at the Scarborough Distribution Center.
In a statement, the Postal Service says "as the market changes, we will continue to evolve, improve, and manage our operations while providing first rate service to the American public."