A REPRIEVE has been granted to Central America's plan for peace and democracy, and it makes possible -- though not certain -- a result that had come to seem increasingly dim. What happened was that the contras tightened the pressure on Managua, while the Central American plan opened up to the Sandinistas an acceptable and positive way to respond. The next few weeks, in which the Sandinistas will have to demonstrate their commitment to democratization while the American political system weighs the question of contra aid, may determine the fate of the region for years.

Daniel Ortega promises immediate delivery on canceling the state of emergency, opening direct talks with the contras on the cease-fire and phasing in a broader amnesty so that contras taking advantage of it can become part of a political dialogue along with other opposition figures at home. His record and his Marxist philosophy compel a rigorous skepticism toward his pronouncements, but the fact remains that if he does what he pledges to do he will be operating within the terms of the Central American plan. The plan does not require the governments that drafted and signed it to make their armed challengers partners in power sharing. It requires them only to open the way for the challengers to join the political process, which, though it is held by the plan to certain higher standards, will still be run by the government.

The consensus that quickly formed in Washington was that good-faith compliance by President Ortega in the next few weeks would moot the question of further contra aid. This very prospect, of course, was what made administration stalwarts and others leery of the plan in the first place: they feared that the plan invited the Sandinistas to take the step they now have taken and to reverse field later after the contra force had been dissolved.

This is not a paper risk. It could happen. The proper hedge against it, however, cannot be to look for ways to undercut the Central American plan. The proper hedge is to hold the Latins to their insistence on moving Nicaragua along the democratic road. There is no taste for Marxism among the other signers of the Arias accord. There is a far greater fear of a rampant Nicaragua than almost anyone in Washington holds. This supplies a powerful incentive for the other Latins to insist on Nicaraguan compliance.