It's time for Ronald Reagan to draw up his political will. With just 15 months remaining in his presidency, Reagan has to decide what he will leave the nation and what, in a sense, he will take with him. One issue that should not go to political probate is his policy toward Nicaragua.

The reasons for that come clear in a Playboy magazine interview with Nicaraguan leader Daniel Ortega. The Sandinista leader is obsessed with Reagan -- maybe as much as Reagan is with him. Speaking more like the bishop of Managua than the coordinator of the Sandinista junta, Ortega said, "I don't think Reagan has been illuminated by God. I think he's closer to the darkness of the devil." Man or devil, Reagan is out to get him, Ortega thinks.

And indeed he is. Without much political support, the president has plunged Nicaragua into a U.S.-financed civil war. His fierce determination has goaded a reluctant Congress into funding the contras, and the results have been telling. The Nicaraguan economy is a basket case, with inflation running at almost 1,000 percent. The contras probably will never win, but they have the capacity to bleed the country almost dry.

Lamentably, the contras have been useful. It's always possible, as Costa Rican President Oscar Arias maintains, that the contra war has provided the Sandinistas the excuse to tighten their grip. But it's possible they would have done so anyway. If that's the case, it's the cost of the war itself that now puts them into a compromising frame of mind.

On Aug. 7, the Central American presidents, including Ortega, agreed on a regional peace plan. Among other things, it requires that Nicaragua restore "political pluralism." The Sandinistas have already taken some steps in that direction. The opposition newspaper La Prensa has resumed publication and the Catholic Church's radio station, Radio Catolica, has returned to the air.

These Sandinista reforms may be temporary. Given the Ortega government's Marxist ideology, skepticism is in order. But since the peace plan was the work of Central Americans and was not imposed by Washington, there is always the chance that Nicaragua will honor it. At any rate, while our interest in Nicaraguan civil liberties is laudable, it is really secondary. Our chief worry is that Nicaragua will become a basing area for a regional communist offensive. The peace plan says that's not supposed to happen.

But now that Reagan has the Sandinistas' attention, he is not inclined to do business with them. Instead, the president has asked Congress for even more contra aid, and even before that the White House rejected a plan by Philip Habib, the administration's former special envoy, to follow up on the Aug. 7 peace plan by going to the region to iron out details with all the Central American governments. Habib, who told friends he had Secretary of State George Shultz's support for the trip, resigned Aug. 14 in frustration and, probably, enlightenment: Reagan does indeed want the Sandinistas to cry uncle.

Several things are wrong with Reagan's approach. As the Playboy interview makes clear, the Sandinistas are the real McCoy -- hardened revolutionaries. They have been at their business a long time, and some of them, including Ortega, were imprisoned and tortured before overthrowing the Somoza regime. Ortega's recounting of his experiences does not make easy reading. This is not a man likely to cry uncle. In fact, this is not a man likely to cry.

Second, there's little likelihood that the contras can accomplish their goal. They have yet to establish a military base within Nicaragua, and they have yet to propound a political program that appeals to most Nicaraguans. A country besotted with historical anti-Americanism is not likely to embrace a movement created and financed by the CIA.

Ortega knows this as well as anyone. He correctly identifies the president as his chief enemy, and he must wonder, with a fair degree of hope, who will come after Reagan. If it's a Democrat, he has little to fear. All the Democratic candidates oppose contra aid. They would let Nicaragua be Nicaragua -- as long as it poses no threat to the United States. As for the Republican hopefuls, they are a hawkish lot, but do not have the commanding political skills of Reagan. If he cannot get the United States to support the contras enthusiastically, how can they?

Like the old man who sings "September Song," Ronald Reagan's days as president are winding down. The president can either dispose of the Nicaragua problem now, on the best terms he is likely ever to get, or leave it in his political will for a successor. He would be wise to take it with hi