The first break for President Carter's new "small steps" policy in wooing anti-Sadat Arabs to his Mideast peace plan came Sept. 29 when the way was finally cleared for Congress to give Syria, leading the Arab resistance to the Camp David accords, [WORD ILLEGIBLE] million in non-military aid.

The entire aid package for Syria had been thoughtlessly dumped from the House version of the aid bill months ago. The extraordinary reversal by the House conferees after Camp David resulted from hours of telephone calls to House members by Carter's aides, led by National Security Adviser Zhigniew Brezerinski. Here was the first success for the "small steps" policy.

With Carter's plan for peace in the Arab-populated. Israeli-coutrolled West Bank and Gaza hanging on Arab willingness to cooperate, such small steps mark the limit of presidential room for maneuver to keep the non-Egyptian part of his peace deal from collapsing. But it may be enough.

Syria's President Hafez Assad is chief architect of an anti-Egyptian front to isolate President Anwar Sadat for making a separate peace. Giving him the full U.S. aid will not change Assad's mind overnight. But it is Carter's way of sending this message to skeptical Arab leaders. The United States did not convene the Camp David summit to underwrite a separate peace, the United States will not permit Israeli Prime Minister Menachem Begin to sabotage the West Bank and Gaza agreements.

Similar stroking, mixed with U.S. muscle, is being applied backstage to Jordan's King Hussein and, most important, to Saudi Arabia. Carter aides are really more concerned about Saudi reactions than they admit. "The Saudis are absolutely crucial," one top adviser told us, "and they haven't given us the slightest signal of coming aboard."

The heart of Jimmy Carter's difficulty in winning the trust of the angry Arab world lies in Israeli politics. Begin barely squeezed out a onevote majority in his own hard-line Herut Party when the Israeli parliament overwhelmingly approved the Israeli-Egyptian peace agreement.

To achieve even that razor-edge margin, Begin angrily disavowed a public pledge by Carter that no new Jewish settlement would be constructed on the West Bank during negotiations for a West Bank-Gaza settlement. After that vote, Israeli supporters in Congress insisted that if Begin had not been able to win the support of the Herut, he would have resign as prime minister, throwing Israel into political crisis.

Both the United States and Israeli now agree to disagree on the explosive settlements issue, which is the Arab litmus test of U.S. intentions on the West Bank. Carter does not yet dare to force the issue over settlements with Begin for fear of undermining the prime minister at home. But until the Arab world is certain that Israel will be forced to stop colonizing the West Bank, the cooperation of Jordan and West Bank Arab leaders remains doubtful.

Accordingly, Carter's switch from the grand stage of Camp David to an undramatic policy of "small steps" is the only way open to him for now. But as the Israeli-Egyptian peace process moves along, there inevitably will be a showdown over new settlements. In that showdown, the president will have powerful cards to play.

Chief of these is the transformed mood in Congress, particularly within the potent Israeli bloc. Begin has never been popular with the American Jewish community, and the Camp David agreements did not change that. Rather, a surprising sentiment has emerged that is in total conflict with Begin's biblical claims to the West Bank.

Israel's supporters in Congress have carefully avoided taking place sides in the Carter-Begin dispute over who said what at Camp David about new settlements. But the word has been passed privately to the president that when the settlements showdown comes, he will have full political backing on Capitol Hill - long the protector of Israel's interests whenever a president applied.

The showdown will be delayed until Israel and Egypt are well along the road to their separate peace and the rest of the Arab world faces the reality of that sweeping transformation of Mideast politics. Soothing the Arab world with small steps until he can safely come to terms on new settlements is Carter's only course, but so far it seems to be working well.