By Emily Stephenson
WASHINGTON (Reuters) - The U.S. Postal Service's regulator has rejected an attempt by a postal workers' union to block changes to mail delivery set to take effect next week, the Postal Regulatory Commission said on Friday.
The mail agency said in May it would begin this summer consolidating operations at mail processing plants, with about 140 facilities to be closed or consolidated by February 2013.
As part of the cost-cutting steps that begin July 1, the Postal Service would shrink the area in which customers can expect mail to be delivered the next day.
The American Postal Workers Union, which represents mail clerks and other workers, filed a complaint earlier this month arguing that USPS cannot begin implementing the changes until it receives an advisory opinion from its regulator.
The union asked the Postal Regulatory Commission to block the service changes until the commission rules on the complaint.
Regulators are still considering the APWU's initial complaint but said Friday they denied the request for an emergency injunction preventing the service changes.
"The potential harm to the Postal Service from a preliminary injunction outweighs the potential harm to mailers from not issuing a preliminary injunction," the commission said.
Postal officials have been scrambling to staunch annual losses of billions of dollars as mail volumes dip and massive payments to the federal government for future retiree benefits and other requirements drain its cash.
The agency lost $3.2 billion in the first three months of 2012. Congress is weighing a number of options for helping restore the Postal Service to profitability, including ending Saturday mail delivery, but the House of Representatives and the Senate have yet to agree on a plan.
USPS officials say they need to begin closing facilities and making other cost-cutting moves in the meantime. The Postal Service initially planned to close about 220 processing sites and end next-day delivery. The plan was later modified to spread out the closures and maintain overnight delivery of local mail for a few years.
The agency also announced in May it was abandoning for now a plan to close thousands of post offices and said instead it would reduce operating hours at 13,000 low-traffic offices.
Postal unions and some business mailers have argued that slowing delivery and other service changes could hurt the Postal Service by causing businesses and individuals to send less mail.
(Reporting By Emily Stephenson; Editing by Andrea Ricci)