If Congress approves a proposal to eliminate Saturday deliveries by the U. S. Postal Service, as many as 300 local jobs will be lost, postal union officials fear.

Postal Service officials decline to predict a number for job cuts. They say that if the Saturday deliveries are stopped, the Postal Service will not replace workers who retire, will eliminate the jobs of temporary letter carriers and will cut back on overtime.

U. S. Postmaster John E. Potter proposed last month the nationwide elimination of Saturday deliveries as part of a cost-saving plan. The Postal Service, which has been losing business to e-mail and online bill-paying, forecasts a $238 billion deficit over the next decade if no changes are made.

Eliminating Saturday service is far from a done deal, however, because Congress would need to approve it.

Postal worker unions, fearing the potential loss of 40,000 jobs throughout the country, are lobbying hard to persuade Congress to oppose the move.

“The jobs are important, but this isn’t just about jobs,” said Robert J. McLennan, president of Branch 3 of the National Association of Letter Carriers. “We think this would be a bad move for us, for the Postal Service and for our customers. That’s why we’re lobbying against it with everything we’ve got.”

McLennan’s local is based in Cheektowaga and represents 1,500 letter carriers in the Western New York postal district. Arthur J. Muoio is president of the union’s Rochesterbased Branch 210, representing 1,000 carriers in the district.

Stopping Saturday service could eliminate as many as 300 Western New York jobs, the two union officials estimate, most of them letter carriers who are called temporary employees. Many now work full time, filling in as needed for other carriers.

“These are good jobs that eventually would be lost to this community,” McLennan said.

He noted that full-time letter carriers make between $42,610 and $55,794 a year, in addition to pension and health benefits.

There is no doubt that in the years ahead, the Postal Service will be a shrinking work force, said Karen Mazurkiewicz, Western New York communication coordinator for the Postal Service.

But Mazurkiewicz said she could not comment on the union’s estimate of up to 300 potential job losses because no numbers have been specified yet.

“From everything I have seen from the postmaster general, the plan does not call for layoffs,” Mazurkiewicz said. “Cutting Saturday service is just one part of a plan to make the Postal Service more viable for some difficult years ahead. We are getting more efficient with new technology. We’re consolidating mail routes to make operations more efficient.”

The Postal Service has been one of the region’s larger employers for decades. Currently, more than 6,200 people work for the Postal Service in Western New York, with annual salaries and benefits of $501 million.

But the increased use of e-mail and Internet bill-paying has been a nightmare for the Postal Service, both nationwide and locally. The service delivered 36 billion fewer pieces of mail in its 2009 fiscal year than it did in 2007. The numbers in Western New York are down sharply, too.

At the same time, many Americans use the Postal Service every day. Mazurkiewicz noted that the service delivered 177 billion pieces of mail last year.

But the service has serious financial problems. Potter said last year it was facing an “acute financial crisis.” He recently proposed ending Saturday deliveries as one way out of the crisis.

The Postal Service hopes to stop Saturday deliveries early in 2011.

Fifty local mail delivery trucks now have global positioning system devices so bosses can find out where their carriers are at any given moment. And all mail carriers must use an electronic device to zap bar codes at various locations on their routes, to prove they are moving up to speed.

Those changes were put into effect to increase efficiency, Mazurkiewicz said.

Union officials contend that other steps can be taken to help the Postal Service, instead of cutting Saturday mail deliveries.

Union and Postal Service officials say the nationwide pension system for postal retirees is overfunded by $75 billion. Postal officials are trying to persuade Congress to return that money to the Postal Service so it can be used to fund mail deliveries.

If the $75 billion were recovered, there would be no need to cut the frequency of deliveries, according to the union.