TOLEDO — The U.S. Postal Service announced Monday it is pursuing plans to shut down the Toledo mail processing center near downtown, and 251 other such plants nationwide, in order to reduce its costs by $3 billion a year.As part of the plan announced Monday in Washington, the Postal Service would lengthen its standards for delivering first-class mail, from one to three days to two to three days. U.S. Rep. Marcy Kaptur, D-Toledo, blasted the postal service’s plans as ill-planned and hasty — and threatening the jobs of 400 people working at the Toledo facility.”We are concerned that the established guidelines and procedures are not being followed,” Kaptur wrote in a letter calling for a Government Accountability Office audit. ”The Toledo Mail Processing Plant is an essential piece of the Ohio’s successful USPS operations.”The 400 ”dedicated, highly capable public servants” at the Toledo Processing Plant on South St. Clair Street absorbed the functions of the Lima Processing Plant last summer, Kaptur noted. She said the Toledo plant is rated as one of the nation’s most productive and efficient facilities.The Postal Service on Monday took a procedural step towards fulfilling its plan to shut down what it says are under-used facilities and to impose slower standards for the delivery of first-class mail.The cash-strapped agency’s goal is to eliminate 252 of the nation’s 461 processing centers by spring. Nearly 30,000 workers would be laid off as the post office struggles to respond to a market shift to online communication and bill payments.The cuts are part of $3 billion in reductions aimed at helping the agency avert bankruptcy next year. They would virtually eliminate the chance for stamped letters to arrive the next day, a change in standards that have been in place since 1971.The plan technically must await an advisory opinion from the independent Postal Regulatory Commission, slated for next March. But that opinion is nonbinding, and only substantial pressure from Congress, businesses, or the public might deter far-reaching cuts.Postal authorities said they had not made any final decisions, or issued notices of any closures.”What happened is the U.S. Postal Service presented a proposal to the postal regulatory commission,” said David Van Allen, spokesman for the Cleveland office of the postal service. ”It does not make it a done deal. It is a continuation of the ultimate plan,” Van Allen said.In addition, 3,700 post offices are under review for shutdown. In Toledo, five post office stations and branches are on the list: Manhattan Boulevard, Point Place, Old West End, East Toledo, and Dorr Street.Rural post offices in northwest Ohio that are targeted for closing include Burgoon, Clay Center, Farmer, Hoytville, Latty, Kunkle, Mark Center, Mount Cory, Rocky Ridge, West Millgrove, and the Isle St. George post office in the Lake Erie Islands. In southeast Michigan, the post office in Mosherville, Hillsdale County, has been identified for study.Van Allen said the Postal Service is trying to deal with a decline in the use of first-class mail.”We’re trying to optimize our network to use our plants to full capacity,” Van Allen said. The 252 targeted processing plants are being used at one-half to two-thirds capacity, he said.The cutbacks are expected to upset many postal customers, especially small businesses and magazine publishers.”The post office is a mainstay of America, and the fact that these services will no longer be available is absolutely crazy,” said Carol Braxton of Naperville, Ill., as she waited in line at a mail sorting center Monday with the holiday shipping season picking up steam.”Well I’m not happy about them, but what else can you do with this economy? If they’re getting ready to go bankrupt, it’s better to cut back than to go totally bankrupt,” said Deborah Butler of Brandywine, Md., who was at a Washington, D.C., post office. ”You still need them. Because everybody can’t afford the other ones, like express mail and things like that. Even though the world is computer literate, everybody doesn’t have computers.”At a news briefing in Washington, postal vice president David Williams said the post office needs to move quickly to cut costs as it seeks to stem five years of red ink amid steadily declining mail volume. After hitting 98 billion pieces in 2006, first-class mail volume is now at less than 78 billion. It is projected to drop by roughly half by 2020.The Postal Service, an independent agency of government, does not receive tax money, but is subject to congressional control on major aspects of its operations. The changes in first-class mail delivery could go into place without permission from Congress.Separate bills that have passed House and Senate committees would give the Postal Service more authority and liquidity to stave off immediate bankruptcy. But prospects are somewhat dim for final congressional action on those bills anytime soon, especially if the measures are seen in an election year as promoting layoffs and cuts to neighborhood post offices.The Associated Press contributed to this report.