THE LOOMING FIGHT to repeal the Byrd Amendment will pose for the Carter administration the first important test of whether it can conduct not only a right-minded but an effective African policy. For the amendment, permitting importation of Rhodesian chrome despite the United States' formal pledge in the United Nations to halt such trade, has become in the six years since its passage the symbol of lingering American support for white minority rule. As long as this legislation has been on the books, the United States has stood open to the charge that, while it favored majority rule in pronouncement and principle, it supported minority rule in practice.

In white Africa, the Byrd Amendment seems to have had a meaning that too few Americans have read. It has meant that, when finally forced to choose between its investments in the white-dominated economies of southern Africa and its commitment to black liberation, Americans would go with their money. No one will ever be able to tell, for instance, the precise extent to which the Byrd Amendment has nourished Ian Smith's evident judgment that the United States would, in the end, bail him out. But it seems to us incontrovertible that the amendment directly undercuts the current American effort to induce his white regime to negotiate promptly an acceptable transition to majority rule. This makes repeal an operational urgency as well as a symbolic one.

The Nixon and Ford administrations never saw fit to expend the political capital needed to fight the battle through in the Congress; in those years, the Senate voted for repeal but the House would not. The Carter administration's good faith on this issue is nowhere seriously challenged. But support for the amendment has become an article of faith on the political right, especially among those who identify it with a passionate hostility to the United Nations. One part of the opposition collapsed yesterday when Rep. John Dent (D-Pa.), who represents a district whose specialty-steel plants use Rhodesian ores and who has been the chief House sponsor of the Byrd Amendment, announced that the development of new technology has now made it possible for the United States to do without Rhodesian chrome entirely. But Mr. Carter will still have his work cut out for him.