"With the authority to move to a schedule that includes six days of package delivery and five days of mail delivery, the Postal Service can save nearly $2 billion annually," Postmaster General Patrick Donahoe told the House Committee on Oversight and Government Reform.
"The American public supports this delivery schedule and it's the financially responsible step to take," he said.
But labor unions, lawmakers representing rural districts and some private mailers oppose the cutback.
Donahoe tried in February to drop Saturday delivery without congressional approval. But he backed down in April after lawmakers objected.
He said he was acting out of desperation because Congress didn't approve a restructuring plan for the mail agency, which lost $15.9 billion last year.
"We cannot pretend these marketplace changes aren't happening or that they don't require fundamental changes to our business model," Donahoe said. "We need comprehensive reform now."
Committee Chairman Darrell Issa, R-Calif., supported Donahoe's appeal to end the Saturday delivery.
Issa himself proposed five-day delivery as well as an end to curbside mail delivery. He proposed post office boxes or clustered boxes on street corners instead, saying the change could save at least $4 billion a year.
Donahoe testified Wednesday every door-to-door delivery costs $353, while cluster-box delivery costs $161.
Rep. Elijah Cummings of Maryland, the committee's top Democrat, said both parts of Issa's proposal would inappropriately cut jobs.
"We're at the point now where the more rightsizing we do, the more the mail is delayed and it loses its value to the customer," The Washington Post quoted him as saying.
Cummings introduced a separate bill that would let the Postal Service get new income by delivering beer and wine, which it's currently not allowed to do.
His bill would also limit executive pay and cancel bonuses if budget-balancing targets aren't met and would shrink the workforce through buyouts rather than by nullifying contracts.
The measure would additionally create a chief innovation officer who would seek non-postal products and services -- such as logistics management, warehousing, security and public Internet access -- to boost revenue.
"If we reject extreme measures ... I believe we can identify common-sense provisions that provide common-ground solutions," Cummings said.
The Postal Service has struggled to stay financially solvent as mail volume plummets due to the Internet and email.
The agency is also constrained by a $5.5 billion yearly payment for health benefits for future retirees.
Donahoe said the prepayment leads to $10,000 in health payments for retirees over 65, "when we should be paying $3,500."