HARD AS IT may be to believe, every once in a while the federal government makes a mistake. That seems to be what happened about a dozen years ago when the formula was created that dictates how much doctors are paid for treating Medicare patients.

According to Medicare chief Tom Scully, the fee schedule was miscalculated so that doctors were overpaid for a year or two in the late 1990s but are now facing a second year of fee cuts so deep that he fears many will refuse to treat Medicare patients, joining a physician exodus from Medicare already well under way.

Mr. Scully can fix this, he says, if Congress makes a technical correction before it adjourns for the year, probably this week. And the House included corrective language in a much larger measure passed Thursday.

But the Senate is balking at a quick fix for doctors when other Medicare providers, such as hospitals and nursing homes, also deserve a fee boost that can't be achieved so easily.

That's a short-sighted view -- no doubt driven by lobbyists for the other providers -- that senators should reconsider before they go home.

If Congress fails to act quickly to fix this mistake, it will not only anger doctors and patients but also endanger the health of elderly Americans.

Physicians may not be a group that inspires much sympathy. People assume doctors are wealthy. But thanks to managed care and other pressures to hold down costs, the medical profession is not nearly as lucrative as it once was -- especially for primary care doctors on the front lines.

No one in business survives long with reduced income. Yet Medicare payments to doctors dropped 5.4 percent this year and are scheduled to decrease by an additional 4.4 percent beginning Jan. 1. That means, for example, that the fee for a basic office visit for which doctors were paid $31.45 in 1993 -- and which rose to a high of $38.20 -- dropped to $36.20 this year. Without corrective action, it will drop further to $34 in January.

Thanks to the 1997 law that balanced the budget, payments to all Medicare providers were squeezed so tightly that Congress has been forced to restore some of the money to keep them in business. All acknowledge that more needs to be done.

But the House and Senate have been at odds for months over how large to make the package of so-called "givebacks," ranging from $30 billion to $43 billion over 10 years.

Time has run out on this session of Congress for such a large and costly undertaking to be compromised into final form and voted on by both houses. Sen. Bill Frist, a Tennessee Republican and a heart surgeon, says he will press for comprehensive action on Medicare issues early next year.

Meanwhile, senators should not let the broader dispute prevent them from acting now to help doctors who have been the hardest-hit and are the easiest to help.