In its move to cut Saturday delivery of first class mail, the U.S. Postal Service is taking advantage of one piece of congressional indecision to maneuver around another.

It’s a stark example of gridlock in D.C.

The Postal Service gets no tax money for its operations but is still subject to congressional control, and taxpayers could still be on the hook for its retirement obligations. While the service has been losing billions of dollars each year, its suggestions for cutbacks have been rejected by Congress, which has failed to agree on a plan of its own.

But in an ironic twist, the ruling that prohibits the Postal Service from cutting back to five-day delivery is in an appropriations bill that Congress hasn’t passed. The Postal Service has decided that allows it to act on its own, according to a report in the Huffington Post. Congress could reimpose the ban after March 27 when its temporary spending measure expires.

In the meantime, Postmaster General and CEO Patrick Donahoe announced Wednesday that Saturday delivery of letters will stop in the week of Aug. 5, although package delivery will continue six days a week. That reflects the one fiscal bright spot for the service: package revenue grew 8.7 percent during fiscal 2012, a result of increasing online shopping.

The Saturday cutback and the increased package revenue are not nearly enough to solve the Postal Service’s problems, however. The service lost nearly $16 billion last fiscal year, and additional restructuring is needed. Some critics say the biggest culprit is Congress’ decision to require large payments to make up for unfunded future retiree benefits.

The Postal Service says it has surveys indicating 7 in 10 Americans support the five-day delivery approach, although the letter carriers’ union is vehemently opposed.

We find the five-day plan far preferable to earlier suggestions that rural post offices be shuttered completely. Restructuring and cutbacks are clearly needed, but the needs of rural America must get careful attention.

Congress needs to lead, not obstruct, in the re-envisioning of the Postal Service. And it must assure that small-town America’s unique needs are not ignored.