Thanks to the Sandinistas' hot pursuit across the Honduran border and their cold shoulder of regional (Contadora) peace-making efforts, only modest compromises may be needed for the Reagan administration to turn around a handful of Democratic votes in the House and have its way on aid to the Nicaraguan contras. More than enough House Democrats may welcome the opportunity to slip the inevitable round-house Republican punches of "soft on communism" in an election year.

But if the House does reverse itself the second time around, scheduled for this week, nobody should be in any doubt about what's going on. The outcome will turn, not on sober consideration of sound policy, but on considerations of domestic politics. The swing voters inhe House may find it easy to explain what they are voting against: communism. It was never hard to show that withholding contra aid would simplify life for the Sandinistas.

Whether it would also give running room for regional diplomacy, in an atmosphere free of overbearing U.S. intervention, is the crucial question. And you cannot set it aside without having made some effort to balance the risks between a)abandoning the contras, and b)doing what White House Chief of Staff Donald Regan has told us, in the course of two remarkable TV talk shows, that the administration is trying to do.

I have in mind a Regan appearance on "Meet the Press" in mid-March (where he was introduced as "the next best source" to the president himself) and an interview a week after on ABC's "This Week with David Brinkley." Nowhere else are you likely to find such damning reinforcement of the arguments of those who believe that Ronald Reagan has a crystal-clear view of where he wants to wind up in Nicaragua and only the dimmest sense of how to get there.

Regan minced no words on "Meet the Press": "We have a very aggressive communist nation in our hemisphere for the first time. . . . We have to get rid of it in some way or another. And what we want to do is to try to help those who are trying to overthrow that communist government, try to force it to have free elections . . . "

Were we getting into "the kind of slowly escalating commitment that got us into Vietnam?" No: "We've been assured by the contras themselves that that's more than enough money to take care of them." Vietnam was "absolutely" not the right analogy.

He tried El Salvador. It was "about to go communist" when "we rescued that nation," he said, apparently forgetting that El Salvador had thrown back the rebels' "final offensive" the month before the Reagan administration came to power.

"We did the same thing for Grenada," Regan claimed, inviting a truly frightening analogy when you consider that it took 7,000 American troops to subdue some 700 Cuban combat engineers. Regan went blithely on to say that, "Now we want to do the same thing for Nicaragua." The same thing? A 10-to-1 ratio of U.S. troops to defenders in Grenada is something to think about when you also think about a Nicaraguan armed forces numbering anywhere from 60,000 to 150,000 and of the 10,000 to 20,000 contras -- depending on which estimates you accept.

Regan dragged in the Philippines. He said negotiations had been tried with the contras; all that happened was that the Soviet Union and Cuba sent more supplies. Never mind that the thing might happen again; we must "push, push, push on them, and as a result of that pushing they will come toward elections. It's what we had in the Philippines, and it's exactly what we want here." What we had in the Philippines was Ferdinand Marcos, a staunchly anticommunist ally.

OnWeek With David Brinkley," Regan fetched up in Eastern Europe. He argued that if the contras get military aid and the Sandinistas see they are losing, "I think they'll start to bargain -- that is the history of communism." Aghast, the questioners asked for some historical documentation. His answer was that there was pressure against "Poland, Hungary, a few other places" to give way to the "ballot box. . . . They wouldn't agree to do it. They got shown up for what they are. Probably the same thing would happen in Nicaragua."

The "same thing" would be continuing communist rule in Nicaragua. What would the president do next, having "shown the Sandinistas up for what they are"? Regan's answer was that "we'll have $100 million, a lot of water will go under the bridge. I think we'll answer that question as we get closer to the end of the 18 months."

If that is not a prescription for an open-ended commitment -- with no fixed limit on U.S. involvement -- congressional supporters of the administration's policy in Nicaragua will at least owe us an explanation of what, then, it is that they think they are voting for.