THE National Endowment for Democracy (NED) didn't topple the communist governments of Eastern Europe in 1989, but it gave them a shove. It didn't elect Violeta Chamorro president of Nicaragua last year, but it helped embolden voters. The endowment can't take credit for the surge of democracy in Latin America, Asia, and Africa, but it's quietly working to build and sustain the momentum.The endowment was created by Congress in 1984 to nurture democratic seedlings in oppressed countries. Since then, NED has laid out about $152 million in grants to small organizations for voter education, training of democratic activists, support of alternative press and publishing activities in closed societies, and building free trade unions. But the endowment finds itself under fire in Congress. It has always had some critics: liberals who think the endowment's grantees are too rightist, conservatives who regard its efforts as too interventionist. In March a report by the General Accounting Office (GAO) was released that concluded that the endowment's procedures for evaluating grantees' programs are inadequate, and that some grants have been misused, mismanaged, or not effectively accounted for. Last month, opponents in the House proposed a drastic cut in the endowment's budget for fiscal 1992. Facing a hostile debate, a NED supporter deleted the agency's funding altogether, intending to restore it later in negotiations with the Senate. Some of the GAO findings seem overstated. They call for a precision in evaluating grantee programs that many don't lend themselves to, and the GAO may have underestimated the accounting difficulties of small groups of democratic activists often operating under trying conditions. Still, NED funds should be managed prudently and with as much accountability as possible. The endowment's board has accepted the thrust of the GAO report and is preparing a report to Congress on remedial steps it's taking. No doubt NED's operations can be improved. But with democracy on the march around the globe, now is hardly the time for Congress to withhold from this useful agency what is, by Washington standards, pocket change.