THE RESCUE of the Chrysler Corporation is proving to be even riskier and more expensive than Congress expected last winter. When it originally authorized the loan guarantee in December, Congress set a long list of explicit conditions. The Senate Banking Committee intends to hold hearings next week on the manner in which the administration has now bent and squeezed those legal requirements. It is utterly unlikely that many people in Congress will actually vote to reverse the administration's decision, since that would plunge the company into immediate bankruptcy. But the committee's chairman, Sen. William Proxmire, is absolutely right in forcing his colleagues to consider a bit more carefully the precedent that they are setting.

Last December, Congress also established a Loan Guarantee Board -- in effect, the Treasury Department -- to see that the conditions were met. Those conditions have turned out to be far more difficult than almost anyone expected. Chrysler's losses over the winter ran well above any previous estimate. With a recession beginning, federal pressure on the banks to extend unguaranteed matching loans seemed increasingly questionable. Finally, last weekend, the Loan Guarantee Board simply deemed the congressional requirements to have been met.

What public interest does this venture in corporate first aid serve? It's necessary to acknowledge that there are a couple of benefits. A large bankruptcy at this moment, with the economy already contracting, could only further discourage investment and lending. It would certainly give new momentum to the campaign, by some of the automobile industry, to get protection from foreign competition. The White House is entitled to great credit, incidentally, for resisting the Detroit protectionists.

But the irony of the federal rescue is that the result is not likely, in the end, to turn out very differently from the bankruptcy that it is supposed to avert. In either case, some parts of the corporation would prove profitable and survive -- and some would not. The most useful work of the Loan Guarantee Board in the months ahead will be to keep Chrysler on its reducing diet. The corporation has already sold off its overseas operations, and it plans to drop some of its present lines of production. Further sales of subsidiaries are evidently ahead, as the corporation can find buyers.

Chrysler is being turned into a smaller company, but its future remains highly uncertain. For Congress, the lesson is that even very large amounts of federal aid do not necessarily buy security and prosperity for a company in trouble.