SCARBOROUGH — A labor union official said transfer of a mail-sorting machine will mean slower deliveries for southern Maine postal customers and uncertain futures for more than a dozen postal workers.

Scott Adams, general president of Local 458 of the American Postal Workers Union, said the changes at the U.S. Postal Service Southern Maine Processing and Distribution Center at 79 Postal Way will impact two dozen of the facility’s nearly 480 jobs.

About half of the job issues will be resolved through attrition or reassignments, Adams said.

Also because of the change, as of July 1 priority mail originating in southern Maine will take two days for delivery instead of one.

Eleven mail handlers who work under the National Postal Mail Handlers Union could be relocated or reassigned. Twelve clerks under the APWU were offered other jobs in Scarborough, and the union may need to find two maintenance workers alternative jobs next February, Adams said.

Christine Dugas, a U.S. Postal Service official in Providence, Rhode Island, said the service is moving one of two machines that sort parcels and bundled magazines from the Scarborough center to a facility in Nashua, New Hampshire.

She called the move “a routine operational change.”

Adams said about 1, 000-2,000 pieces could be delayed each day because in-state and out-of-state mail sometimes gets intermingled. Previously, local postal workers could correct the mistake by moving mail from one machine to the other. But now that type of mail will be headed to New Hampshire before the mistakes are found and re-routed back to Maine.

In a letter to Postmaster General Megan J. Brennan, U.S. Sen. Angus King, I-Maine, said he is “concerned such a move would result in delayed mail and reduced service standards, particularly during ‘peak season.’ Such a course of action cannot but raise the possibility of difficulty for Maine businesses who have come to rely upon USPS.”

Adams said the union asked the USPS to delay the machinery transfer. But maintenance workers have already started removing safety barriers surrounding the machinery, he said, and a team is supposed to arrive soon to remove it.

The work could take about a week to complete, depending on the size of the crew. The machine was last used on an overnight shift June 29, Adams said, before being powered down.

He said he was informed in February that “in order to improve service, moving machines can be beneficial.” But he said there was no mention of changing delivery standards.

It may still be possible for mail to reach people within a day, but the Postal Service will now only be offering priority two-day service before forcing customers to upgrade.

“Priority within the Southern Maine area will now be a two-day product but priority mail destined to a large portion of New Hampshire and Massachusetts will now be overnight,” Adams said in a letter to state Rep. Chellie Pingree, D-Maine.

“While our commitment to retain jobs in Maine never alters, this issue was clearly about the reduction in services,” Adams wrote. “Maine citizens deserve quality service. However, they will now be afforded (the opportunity) to use priority mail service over first class with no additional benefit. The only option for next-day service in Southern Maine will be overnight priority express mail.”

Dugas, meanwhile, said the Postal Service “prudently match(es) our workforce to the workload and continuously adjust(s) staffing to deliver the most efficient, record-level service to our customers. As the market changes, we will continue to evolve, improve and manage our operations while providing first-rate service to the American public.”

The Scarborough postal center is one of two in Maine. The other is in Hampden.

 Melanie Sochan can be reached at 781-3661 ext.106 or msochan@theforecaster.net. Follow her on Twitter @melaniesochan.