AN ISSUE as controversial as abortion will not pass readily from the American political scene. But the Senate's rejection this week of a proposed constitutional amendment opening the way to bans on abortion must be viewed as an important setback to those seeking to make the procedure illegal.

This was the first opportunity for either body of Congress to vote on a constitutional amendment overturning the Supreme Court's 1973 decision--and its recent reaffirmations of that decision--striking down most obstacles to a legal abortion. The vote was thus free of the ambiguity surrounding other efforts to rewrite the Supreme Court's judgment by a simple act of Congress. Sen. Jesse Helms, a leading abortion opponent, did not vote in favor of the amendment because, by simply permitting legislatures to outlaw abortions, it did not go far enough. But for other members the vote was a clear opportunity to register an opinion on the desirability of allowing Congress or state legislatures to place additional legal restrictions on access to abortion.

It is also significant that the vote came after extensive public attention to the issue and at a time when anti-abortion forces were assumed to be politically powerful. The case against legalized abortion has been made strongly and repeatedly by the president and by politicians and political groups who scored major electoral victories in 1980. Yet proponents found they could not command a simple majority in the Senate, let alone the two-thirds vote required for passage of a constitutional amendment.

Sen. Helms has vowed to continue to push his legislative proposals to restrict access to legal abortion. But he is unlikely to command a larger Senate following for these approaches, which involve intrusions into judicial authority that are of questionable constitutionality. Advocates on both sides will also renew their efforts to convince the public of the rightness of their position. The debate will continue. But perhaps there is hope that each side is learning to be more tolerant--if not of the other's point of view, at least of the fact that this is an issue on which most people will continue to feel deeply ambivalent. On such an issue, moral suasion rather than legal sanction is the appropriate tactic.