WASHINGTON (AP) — Apparently trying an end-run around an unaccommodating Congress, the financially struggling U.S. Postal Service says it will stop delivering mail on Saturdays but continue to disburse packages six days a week.

In an announcement scheduled for later Wednesday, the service is expected to say the Saturday mail cutback would begin in August and could save $2 billion annually.

The move accentuates one of the agency's strong points — package delivery has increased by 14 percent since 2010, officials say, while the delivery of letters and other mail has declined with the increasing use of email and other Internet services.

Under the new plan, mail would be delivered to homes and businesses only from Monday through Friday, but would still be delivered to post office boxes on Saturdays. Post offices now open on Saturdays would remain open on Saturdays.

Over the past several years, the Postal Service has advocated shifting to a five-day delivery schedule for mail and packages — and it repeatedly but unsuccessfully appealed to Congress to approve the move. Though an independent agency, the service gets no tax dollars for its day-to-day operations but is subject to congressional control.

It was not immediately clear how the service could eliminate Saturday mail without congressional approval.

But the agency clearly thinks it has a majority of the American public on its side regarding the change.

Material prepared for the Wednesday press conference by Patrick R. Donahoe, postmaster general and CEO, says Postal Service market research and other research has indicated that nearly 7 in 10 Americans support the switch to five-day delivery as a way for the Postal Service to reduce costs.

"The Postal Service is advancing an important new approach to delivery that reflects the strong growth of our package business and responds to the financial realities resulting from America's changing mailing habits," Donahoe said in a statement prepared for the announcement. "We developed this approach by working with our customers to understand their delivery needs and by identifying creative ways to generate significant cost savings."

But the president of the National Association of Letter Carriers, Fredric Rolando, said the end of Saturday mail delivery is "a disastrous idea that would have a profoundly negative effect on the Postal Service and on millions of customers," particularly businesses, rural communities, the elderly, the disabled and others who depend on Saturday delivery for commerce and communication.

He said the maneuver by Donahoe to make the change "flouts the will of Congress, as expressed annually over the past 30 years in legislation that mandates six-day delivery."