THE VISIT of an Israeli parliamentary delegation, sent over to stifle American interest in the Saudi "peace plan," is turning out to be very interesting. The delegation has had some predictably sharp words to say about an initiative that Prime Minister Begin had already described as a program to "liquidate Israel by stages." But that is not all. Delegation chairman Moshe Arens described the key Saudi point --acknowledging "the right of the states in the region to live in peace"--as "a step ahead." The Saudis have "gone a little way in our direction," he said, though they still have "a long way to go."

In Israel, meanwhile, a vigorous public examination of the Saudi proposals is being conducted, with some people insisting they are a trap and others asking whether they may not hold some promise. Even as the Israeli cabinet rejected the proposals last August, Wolf Blitzer recalls in the Jerusalem Post, Foreign Minister Yitzhak Shamir noted that they contained "an undertone of Saudi recognition of Israel." The energy minister, Yitzhak Berman, called the proposals an "interesting development" in that they dispensed with the notion of the "mystical religious character" of the Arab-Israeli dispute, leaving it as "a dispute about borders. As such, it can lend itself to solution. . . ."

The people speaking these words, keep in mind, are not American or even European politicians of the sort that anxious Israelis often dismiss as puppets of Arab oil. They are Israelis, and not doves but hawks. They are not likely to be taken in by winks from Riyadh. But, one hopes, they have the sense and purpose to scan any new sign from an Arab source, especially from a Saudi source, for whatever it may hold.

So there is a major opening for the United States to look over the Saudi offer, and to work to improve it, in tandem with Israel. That opportunity could be lost if the administration gets too fuzzy, as the president, for one, has done by his repeated suggestions that the Saudis have already come to the verge of recognizing and negotiating with Israel. These are, of course, the very things this country should be trying to induce the Saudis to do.

No less an opportunity could be lost, however, if the administration were to shy away from testing the Saudi initiative. In that effort the United States must be scrupulously open and above-board in dealing with the Israelis as well as the Saudis. Otherwise, one or the other will suspect a betrayal. But there is nothing to lose--and conceivably much to gain--in continuing to look to Riyadh. Moshe Arens has it right.