The success or failure of President Carter's skillful mediation at Camp David in building a "framework" for peace now depends not on Egytian President Anwar Sadat or Israeli Prime Minister Menachem Begin but squarely on Jimmy Carter himself.

The "framework" will not stand alone; it must be fleshed out with the help of moderate, pro-Western Arab powers. Only the president has the political clout to expand the promise of Camp David - a dramatic display of U.S. mediation unprecedented in American history - into the Mideast peace Carter has worked so hard for.

The president's clever handling of Sadat's demand for eventual Arab sovereignty on the West Bank shows how indispensable his role was at the summit. Without eventual self-determination for West Bank Palestimians, Sadat insisted, there could be no separate Egyptian-Israeli peace.

Nothing in the documents signed by Sadat and Begin delivers such guarantees. But behind the cold print, return of the Sinai Peninsula to Egypt and eventual return of most of the West Bank to Arab sovereignty were linked together.

"You made a commitment to be a full partner in the peace talks," Sadat said in his solemn, restrained statement Sunday night. "The continuation of your active role is indispensable."

That was Sadat's veiled warning only Carter can make these peace talks successful; if they fail on the West Bank, success between Egypt and Israel is not guaranteed.

Behind Sadat's pointed reminder that Carter continues as a "full partner" were hours of private talks in which the president pledged that if Sadat would sign with Begin, the United States would bring about an end of Israeli rule over 1.5 million Arabs on the West Bank and Gaza.

As former secretary of state Henry Kissinger, who was kept informed of developments throughout the secret talks at the 13-day summit, told us, "The only possibility now is that most of the West Bank will revert to Arab sovereignty."

Begin himself set the stage for this probable outcome. Last winter he promised autonomy, or self rule, to West Bank Arabs with Israel retaining authority over military security. He conceded nothing on Israel's own claim to West Bank sovereignty, a claim backed only by alleged biblical revelations.

But Carter persuaded Begin at Camp David to base a West Bank settlement on United Nations Resolution 242 "in all its parts," with Palestinian autonomy guaranteed. That virtually resolves the sovereignty question.

The ingenious route Carter chose to arrive at this result was persuading Sadat to accept an indirect link between a speedy Egyptian-Israeli peace, to be followed by an Arab-Israeli deal on the West Bank tied directly to Begin's self-rule offer.

Some skeptical administration Mideast specialists suspect that Begin's strategy on the West Bank will be to "screw up" the process of West Bank self-rule, since each step of progress there depends on specific Israeli approval. Likewise, cynical Begin-watchers worry that he will deliberately but secretly plot to have the Israeli parliament vote against his no-new-settlements pledge. That pledge is conditioned on the Knesset's approval.

Cooler heads here dispute such concern. While cautioning that nothing at all is guaranteed, they do not believe Begin or his government would deliberately undermine Begin's own agreement on new Jewish settlements - an essential element of Carter's mediation.

Also essential is help from King Hussein of Jordan, who has no desire to play any role at all on the West Bank. But it would be surprising if he did not come along under pressure. Only Carter can exert it.

The president came down from the Camp David summit with no more than advertised - a "framework" for Mideast peace that can be filled in only if Carter continues what Sadat calls his "indispensable" role as a full partner. Further success will lead not only to a profound change in the bloody Middle East; it will also [WORD ILLEGIBLE] Jimmy Carter as a leader to be reckoned with.