The United States Postal Service says it is nearing a possible default this Friday as the agency must make a multi-billion dollar payment to the federal government.

The Postal Service is legally bound to pay $5.5 billion to the Treasury Department for retiree health benefits. However, it doesn't look like that payment will be made.

U.S. Postmaster General Patrick Donahoe is asking Congress for help.

Donahoe said the Postal Service lost $5.1 billion in the past year. He explained the weak economy and increased use of the Internet have lowered mail volume.

"We are at a point where we require urgent action," Donahoe said.

The Postal Service's losses come despite cutting more than 130,000 jobs and closing some smaller post office branches.

Congress is expected to grant a reprieve by the Friday deadline. However, based on current losses, the Postal Service said it will still run out of money - or come dangerously close - by next September, forcing it to halt service.