NEW YORK -- With America's new Republican Congress talking about cutting foreign aid, those who work in developing countries are already worried that other rich nations will decide to follow the leader rather than take up the slack.


Those in the United States who favor slashing foreign aid say it is time U.S. allies like Japan and Western Europe carry more of the weight, especially considering their reliance on American might for their defense.


They also say it would be unfair to shield foreign aid from the budget-cutter's axe while domestic programs are being targeted.


But many private aid groups and UN agencies are afraid that if the United States stops supporting development work such as building roads, schools and clinics, they could be forced to abandon such projects altogether, since they often use American money as leverage to get financing from other sources.


"Say you've got a big project that's $1 million, and you've already got $500,000 of that from the U.S.," said CARE USA executive administrator Chris Conrad. "Then it's easier to attract other donors. They very much like to be part of something larger, so that they don't have to pay the total project cost."


There also are fears other cash-strapped governments -- far from stepping in to fill the void -- may justify cutting their own overseas assistance by reference to Washington's example.


"It has a definite snowball effect," said Senator Patrick Leahy, former chairman of the Senate Appropriations subcommittee on foreign operations and an opponent of drastic cuts in U.S. aid. "We are still the world's largest economy, and if we cut back, it's hard for other countries to do otherwise."


Japan surpassed the United States as the world's largest aid donor in 1993, mainly because Washington cut aid from $11.7 billion in 1992 to $9 billion. Japan's total was $11.3 billion in 1993.


Twenty other industrial countries also cut their aid budgets that year, leading to an 8 percent drop in the worldwide development effort, said Colin Bradford, assistant administrator for policy at the U.S. Agency for International Development.


Then the dip was attributed to the end of the Cold War, he said. Now the fear is that a downward trend may be developing.


Now Republican Senator Jesse Helms, the new chairman of the Senate Foreign Relations Committee, is preparing a bill that would reduce by up to 35 percent the funds available for Africa, population and environmental programs, aid to Russia and Eastern Europe and agricultural assistance.


Representative Sonny Callahan, new head of the House subcommittee dealing with foreign aid, concedes that what Washington does tends to have "a role model effect" for other major donors. But he said that the United States' allies should not expect Washington to do -- and pay for -- everything.


"If we're going to be the protector of the world and ... the only country with any substantial military, then ... they have to spend a percentage of their gross national product assisting in the humanitarian problems," he said.