Congress has given the U.S. Postal Service some short-term relief from pressing financial obligations but longer-term solutions may require changes such as moving to five-days-per-week mail delivery, U.S. Postmaster General John Potter said Thursday.

The Postal Service is facing up to $5 billion of red ink a year, "so people cannot expect business as usual," Potter said in remarks at the National Press Club. He called for "monumental changes" to remake the Postal Service and allow it to operate in a more business-like way.

Congress agreed last week to slash the amount of money the Postal Service must pay this year to pre-fund retiree health benefits, reducing the obligation to $1.4 billion from $5.4 billion. Potter said the change - which was signed into law by President Barack Obama - is a patch, not a solution to the Postal Service's financial woes.

"We are not going to ask for a bailout," Potter stressed. He also wants to avoid seeking an increase in the Postal Service's $15 billion borrowing authority with the U.S. Treasury Department, saying digging further into debt "is not our goal."

Plans to shutter some post offices and branches, which will be announced on Friday, may save $20 million to $100 million, a fraction of the $5 billion annual budget gap the Postal Service needs to fill.

Options to put the Postal Service back in the black include allowing it to cut back on traditional mail delivery, reduce its workforce and sell more than stamps at its retail outlets.

The Postal Service could save about $3 billion a year by eliminating Saturday mail delivery, an option that Potter said has to be considered given the declines in U.S. mail volume.

Even bigger savings could be realized if Congress lightens the requirement for the Postal Service to pre-fund retiree health benefits, as it agreed to do for 2009. Potter said the Postal Service has "overfunded" the future obligations and could reduce contributions without any harm to retirees.

Asked whether a postal rate-hike might be in the offing, Potter said, "we'll have to make that decision after the new calendar year," and noted that raising rates could be counterproductive if it further depresses mail volume.

Although a weak economy and the growing use of electronic communication have cut into traditional mail, Potter rejected suggestions that the Postal Service is obsolete. He said the Postal Service's revenue is still higher than 95% of the companies in the Fortune 500, and that it has more retail outlets than McDonald's Corp. (MCD), Starbucks Corp. (SBUX) and Wal-Mart Stores Inc. (WMT) combined.

Using post offices to sell cellular telephone services, or as an agent for banks and insurance companies, is another option that the Postmaster General wants to pursue. While Potter said he'd love to jump into the banking business, he's not optimistic on the prospects, summarizing the problem in a single word: "politics."

-By Judith Burns, Dow Jones Newswires; 202-862-6692; Judith.Burns@dowjones.com