WASHINGTON (AP) — The head of the U.S. Postal Services pleaded with Congress Wednesday not to thwart his plan to cut Saturday mail as a way to save money, but postal workers unions criticized the plan as illegal and financially questionable.

Postmaster General Patrick Donahoe told a Senate committee hearing that the plan announced last week is one among a number of steps needed because the agency's financial situation is "dire … more urgent than ever."

The U.S. Postal Service lost $1.3 billion in the final three months of last year, following a nearly $16 billion loss the previous fiscal year. Under the plan announced last week, package delivery would continue Monday through Saturday but about $2 billion could be saved annually by cutting other mail to just five days a week.