THE CLINCH RIVER Breeder Reactor project is in trouble--but its promoters, with characteristic ingenuity, may have found a way to keep it alive. Congress said earlier this year that there was to be no more money for Clinch River unless a better financial plan was enacted. The House has been voting against Clinch River by substantial margins, but it may still have a narrow majority in the Senate. The project's managers now seem to be preparing to attach a financial plan and further funding for the reactor to urgent legislation--perhaps the continuing resolution to keep the government operating after the fiscal year ends on Friday. The House might then find itself with a choice between accepting the continuing resolution, Clinch River and all, or forcing most of the federal government into paralysis.

Those are tactics of desperation on the part of Clinch River's friends and advocates. But tactics of desperation sometimes succeed, and congressmen will have to keep a careful eye on this maneuvering. To allow the Clinch River construction to proceed through this kind of tricky last-minute parliamentary game would mean perpetuating a $4 billion error by the most dubious means.

Congress originally authorized the Clinch River reactor more than a decade ago. It was supposed to be the demonstration of the plutonium breeder technology on a large scale as the prototype of a generation of commercial breeders. But in recent years, the whole economic base for the project has eroded, with huge new discoveries of uranium and the declining forecasts of the need for electricity.

That's why Congress voted earlier to turn the whole thing off, unless its backers could come up with a new financial scheme including greater support from private investors. The backers have come up with a scheme-- and the Reagan administration has endorsed it--that claims to meet that requirement. But on closer inspection, private industry's support turns out to be mainly loans fully covered by federal guarantees and tax breaks. The director of the Congressional Budget Office, Rudolph G. Penner, testified last week that this alleged private support would cost the government more than conventional appropriations would.

That devastating testimony makes it very unlikely that the Clinch River breeder can now get further funding through the usual legislative route. But the end run remains a possibility. Whether it works will depend on the vigilance of the House leadership and particularly its Rules Committee. The degreee of political skill and passion being devoted to the breeder reactor by its partisans is worthy of a better cause.