THE POLISH Communist Party has picked a general to replace the economist who was serving as prime minister. He may be the Soviet bloc's first professional military man to head a government. The switch suggests a party judgment, and a Soviet judgment, that Poland needs firm leadership. But more than that, Poland needs wise leadership. This consists of recognition that the party is disintegrating as a working political institution and that its prospects for restoration depend on its coming to terms with the workers' movement. It cannot be legitimized by military power, Polish or Soviet.

The Polish party formally agreed last August to recognize the independent trade union Solidarity. But it has given millions of workers to believe it means to roll back its concessions as circumstances permit. For instance, it has not purged its own ranks of corruption, political or venal. Workers are now fighting the corruption issue on separate local fronts. It may seen trivial. But it goes to the fundamental question of whether the organization that claims a monopoly of power has any right to it. This is what Polish politics is about

The party is searching for a compromise that will stop the strikes without a military crackdown or Soviet intervention. But the compromise strategy, as in yesterday's decision to let farmers organize in an "association" but not in a "union" is increasingly rickety. A bolder approach may be the only alternative. Perhaps it is not too late for the party to purge itself, to institute broad political and economic reforms, and thereby to restore its credibility with the Polish people. It would wrench the party. How else will the crisis end?

American officials are now expressing semi-publicly their expectation that the Soviets will invade. The Kremlin, it is suggested, cannot countenance consolidation of a center of power not controlled by the Communist Party. This is the received wisdom. But do the officials muttering it understand the implications of what they are doing? They are adding an element of demoralization to a situation grim enough on its own. They are handing Moscow an excuse to invade.

If they must murmur, let them suggest that the Soviet Union may have a grand opportunity. By tolerating the pluralism appropriate to Polish circumstances -- but irrelevant to circumstances elsewhere in the bloc -- the Soviets can hope to strengthen stability on a crucial border and to improve their international standing. To be sure, it is the Polish Communist Party that must make this argument and carry it through in the first instance. But the West is the chorus. The role is not a negligible one.