THERE is no doubt that President Oscar Arias Sanchez was a deserving recipient of the Nobel Peace Prize. His plan for peace in Central America deserves praise. It is judicious, moderate, and, most of all, the best that could have been expected.

Nonetheless, it would be folly for the United States to allow the Sandinistas to use it as a means of eliminating all domestic opposition. Although the Sandinistas' first steps toward political liberalization--the opening of La Prensa and a Catholic radio station--are encouraging, there still are leaps to be taken. And far from moving forward, the Sandinistas may very well, once the contras are eliminated, revoke these all-too-easily-revocable reforms.

The Sandinista government's track record on such reforms does not justify excessive confidence in its sincerity. This is hardly the unambiguously legitimate government that the majority would have us believe. Since the political structure in Nicaragua makes it impossible to determine whether the majority of Nicaraguans consider it legitimate (polling in Nicaragua is prohibited), we can only judge it on its past actions. Would a truly legitimate government need to censor the press, force all opposition candidates out of its "free" presidential elections, and murder, torture, and jail political dissenters? Opposition leaders, such as Edgar Chamorro, Arturo Cruz, Maria Aristides Sanchez, and Miguel Cardinal Obando y Bravo, are surely much more legitimate representatives of the Nicaraguan people than Ortega and the Sandinistas.

There remains hope that the Sandinistas will comply sincerely with the provisions of the Arias plan. But in case they do not, the United States must help the contras remain a viable force. To suggest that merely terminating the United States' support for the Contras will ensure peace in the region and democracy in Nicaragua indicates naivete vis-a-vis Managua, and a measure of self-hatred.