In a letter to Congress, Patrick Donahoe, the postmaster general, described an updated five-year cost-cutting plan put together in coordination with a Wall Street adviser, Evercore Partners. It reiterates many of the mail agency’s proposals to switch to a five-day delivery schedule, raise stamp prices and close about 252 mail-processing centers and 3,700 local post offices. The Postal Service has already asked Congress for permission to make service cuts and reduce annual payments of about $5.5 billion in funding retiree health benefits. But in recent weeks, the Senate and House have stalled as lawmakers differ widely on costs, the level of financial oversight and the prospect of widespread postal closures. On Thursday, Mr. Donahoe said the mail agency’s proposals would enable it to save $20 billion a year by 2015, repay its $12.9 billion debt to the Treasury and return to profitability. The plan, for instance, notes that if the post office could raise stamp prices from 45 cents to 50 cents, either in a single year or over a multiyear period, it could bring in new revenue of about $1 billion. In contrast, Congressional inaction would result in significant annual losses and a “long-term burden to the American taxpayer.” In a news briefing, Joe Corbett, the chief financial officer, said that no formal proposals had been made to increase the price of a first-class stamp. He said the plan described the additional revenue the mail agency could realize over a single or multiyear period if it could increase stamp prices above the rate of inflation. Since 2006, the Postal Service has increased the price of the stamp four times, from 39 cents to 45 cents. About half of the Postal Service’s cost-cutting proposals require legislative approval. Some Congressional proposals have focused on providing short-term relief through a cash infusion to prevent the mail agency’s bankruptcy but also postpone major decisions on cuts until later. Last week, the Postal Service said its quarterly loss rose to $3.3 billion amid declining mail volume and said it could run out of money by October. The agency forecasts a record $14.1 billion loss by the end of this year.