Following the orchestration of President Carter's undisclosed plan to court Menachem Begin, Israel's hard-lining prime minister-designate, Vice President Walter Mondale has been assigned the role of an ally of Israel above suspicion of impure motive.

With Mondale "taking the point," in the phrase of one presidential aide - starting with his major Middle East speech in California this weekend - Carter hopes that even if Begin cannot be won over, American Jewish leaders and Israelis worried about the loss of U.S. support will stay with the President and his peace plan.

At stake is whether the Carter plan works or the Mideast descends into another maelstrom. That plan calls for Israeli withdrawal from most of the Arab lands seized in the 1967 war, a homeland for the Palestinians and secure borders with genuine peace for Israel.

Assigning Mondale the "point" position is smart politics. He has taken the Israeli side in 30 years of Arab-Israeli struggles and has enjoyed inside the politically influential American Jewish community.

Whether these credentials will be enough to defuse the looming crisis in U.S. Israeli relations is far from certain. But at least the assignment shows White House awareness of the mobilization of important parts of the American Jewish leadership against the Carter peace plan since Menachem Begin's public claim to the entire west bank of the Jordan River.

One element of that mobilization appeared early this week when highly respected Rabbi Alexander Schindler, chairman of the conference of president of major Jewish organizations, said he was "frightened" by what "appears to be an erosion of [Carter's] commitment to Israel." Carter's Mideast advisers privately describe those ominous words as Schindler's signal to Israel that he intends to guard Israel's interest in the forthcomig debate. Others, perhaps more realistic, believe that Schindler's public rebuke is the opening shot of the campaign to force radical change in the Carter peace plan.

The main theme of the unfolding Carter orchestration is to smother the new Israeli government with kindness, hoping at least to hold the support of Jewish leaders here, if not change Begin's mind about size of Israel.

Thus, when Shmuel Katz, sent here an advance man for Begin, was invited to the White House for a talk with the National Security Adviser Zbigniew Brzezinski last week, Brzezinski's orders were to "listen quietly" to everything Katz had to say - but not to remonstrated with him. Exactly the same treatment will be accorded to Begin when he arrives here next month for his first meeting with the President.

The orchestration is clear: provided no excuse for a flare-up but leave no particle of doubt that the Carter peace plan remains intact, not susceptible to significant change. In the background of this stratgey are reports now filtering into the White House that both Carter and Brzezinski have been criticized ("harshly" so, according to one diplomatic official) in private sessions conducted by pro-Israeli activists close to the Israeli embassy here.

he case against the President centers on his sometimes glib and often provocative public statements about a Palestinian homeland and "compensation" for Arab refugees evicted from their homes to make way for Israel 30 years ago. Presidential aides perceive in this criticism, however, a possible effort to break down confidence in Carter's credibility as Mideast peacemaker.

Thus, Mondale's instructions are to spell out the administration's total commitment to Carter's plan and emphasize its special attention to Israel's interests: that territorial exchanges must be conditioned on genuine Arab guarantees of peace, with phased stages of withdrawal.

This campaign to win over the American Jewish community, moreover, may find importants allies among Democtatic politicians - quite apart from Mondale - whose pro-Israeli views have undergone subtle modification. Last weekend in Chicago, for example, Sen. Adlai Stevenson warned the national governing council of the American Jewish Congress that although the "commitment" of the United States to Israel is "a heavy burden," it is one "we will continue to accept gladly as long as Israeli interests diverge , he said, Congress "would no more heed the demands of Israel . . . than of the Arab states."

Accordingly, whatever line that Begin presses here next month, the President may have political weapons that Gerald Ford did not have two years ago when pressure from the U.S. Senate forced him into humiliatiing retrreat. Carter intends no retreat.