THE Arias peace plan focused on Nicaragua continues to gain momentum. The fragile web of confidence attained to date should not be undone by disputes in Washington or elsewhere over who is gaining a public relations edge - Daniel Ortega Saavedra, Rep. Jim Wright, or President Reagan. Granted, Managua sought the initiative. In response to repeated pleas from peace plan architect Oscar Arias S'anchez, Nicaragua's President Ortega surprised nearly everyone in agreeing Nov. 5 to indirect cease-fire talks with the contras.
The Reagan administration then said it would wait until next year to ask Congress for more contra aid and, once serious cease-fire talks were under way, would sit down with Managua and other signers of the accord to talk over regional security issues. Both United States actions are positive.
Under Mr. Ortega's detailed but still ``flexible'' cease-fire plan, the contras would move into three safe zones and lay down their weapons by Jan. 5. The contras say the plan sidesteps the important issue of political reform. Ortega says that contras who stop fighting can participate fully in Nicaraguan politics but that certain conditions must be met before any discussions take place.
Members of the Reagan administration were also quick to criticize the Sandinista cease-fire proposal, calling it insufficient to protect contra interests. The administration has also attacked Representative Wright, its one-time peace plan partner, for taking part in last week's Washington meetings between Mr. Ortega and Miguel Cardinal Obando y Bravo, who will serve as mediator in the cease-fire talks. Mr. Wright, who unlike the administration was an early, enthusiastic supporter of the Arias plan, says he was invited to the talks by Cardinal Obando.
The administration has left a vacuum for advocates for peace to fill. Absent an involved president like Jimmy Carter in the Camp David accords on the Middle East, Wright moved in - and why not?
His suggestion of four Americans who could serve as advisers in the truce talks is a good one. Ortega accepts it; the contras are not so sure.
This is a delicate moment. The Central Americans have, in the Arias plan, laid out their own agenda for peace; they know what is acceptable to them and what is not. Many Central Americans, increasingly convinced that Ortega is serious in promising full compliance with the plan, are now optimistic.
The administration, skeptical or not, does not help the situation by keeping a one-sided scorecard on Sandinista moves. Each step is branded as a cosmetic delaying tactic. The White House reasons that to give an inch yields a mile. Short of turning over their government, the Sandinistas will never be able to do enough to satisfy the administration's thirst for a 100 percent democracy in Nicaragua.
An opportunity for peace is at hand. In pressing for everything, the White House may get nothing. Ortega faces pressure not to yield from hard-liners within his own ruling directorate. Continued fighting would likely yield only another round of possibly less satisfactory concessions.
Instead of remaining an aloof judge of whether or not problems get solved, the Reagan administration should directly join the multilateral effort to get them solved. Pressing for peace is the best way to get it.