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."
There was no immediate comment from lawmakers.
But others agreed the Postal Service had little choice but to try.
"If the Congress of the United States refuses to take action to save the U.S. Postal Service, then the Postal Service will have to take action on its own," said corporate communications expert James S. O'Rourke, professor of management at the University of Notre Dame.
He said other action will be needed as well, such as shuttering smaller rural post offices and restructuring employee health care and pension costs.
"It's unclear whether the USPS has the legislative authority to take such actions on its own, but the alternative is the status quo until it is completely cash starved," O'Rourke said in a statement.
The Postal Service is making the announcement Wednesday, more than six months before the switch, to give residential and business customers time to plan and adjust, the statement said.
"The American public understands the financial challenges of the Postal Service and supports these steps as a responsible and reasonable approach to improving our financial situation," Donahoe said. "The Postal Service has a responsibility to take the steps necessary to return to long-term financial stability and ensure the continued affordability of the U.S. Mail."
He said the change would mean a combination of employee reassignment and attrition and is expected to achieve cost savings of approximately $2 billion annually when fully implemented.