In January, the U.S. Postal Service will resume its previously delayed plan to close more processing plants, the agency announced.

The consolidations originally were scheduled for February 2014 but were pushed back for undisclosed reasons. The closures are part of an ongoing effort to streamline postal operations. USPS shuttered about 140 processing centers in the first phase of its “network rationalization” plan and will close an additional 82 in the second phase. USPS maintained 487 processing centers nationwide before the consolidations began in 2012.

The Postal Service has not laid off any employees as a result of the closures, but is instead offering workers relocation options. The agency promised to again follow that blueprint.

“It is projected that these consolidations will result in significant savings for the Postal Service,” USPS wrote in a letter to American Postal Workers Union President Mark Dimondstein on Monday. “Some affected career employees may be reassigned to other vacant positions.” The relocations will be made in accordance with the union’s collective bargaining agreement, USPS said.

The first phase of closures generated annual cost savings of $865 million and resulted in “negligible” service impacts, according to the Postal Service. The renewed effort could signal officials’ pessimism regarding Congress’ ability to pass legislation overhauling the agency. A Senate bill cleared by committee and awaiting a vote on the Senate floor -- introduced before USPS initially decided to delay the consolidation -- would place a two-year moratorium on processing plant closures.

“The uncertainty regarding legislative reform and review of postal rates in the courts continues to delay needed capital investments in network operations and undermined the future financial viability of the Postal Service,” USPS said in a statement.

APWU vowed to fight the closures, noting the Postal Service turned an operating profit last quarter.

“We will make this fight a nationwide campaign and ask all Americans to stand up and fight back,” said Debby Szeredy, the unions executive vice president. “Get ready for the crusade. We cannot sit back and let the [postmaster general] destroy our Postal Service.”