Forty-one years ago Congress told the U.S. Postal Service to start acting like an independent business and pay its own way. Every time the Postal Service tries, something stands in the way: Congress.

Facing annual losses of $18.2 billion by 2015 and a possible default this year, the Postal Service has a five-year plan for profitability. It wants to end Saturday mail delivery, close hundreds of letter-sorting facilities and thousands of post offices and consider breaking union contracts to fire employees. It also wants to set up an independent health plan, raise postal rates and enter lines of business such as delivering wine and liquor.

Each element of the plan has an opponent. Postal worker unions are fighting the closings and job cuts. Direct-mail advertisers and magazine publishers demand Saturday delivery and low rates. Rural constituents — for whom the post office is their strongest link to the rest of the world — and their representatives in Congress protest post office closings.