If Bill Clinton--as we are frequently told--hopes to celebrate an Israeli-Palestinian peace as part of his presidential legacy, he'd better get moving. Time is running short.

No Arab-Israeli agreement has ever been reached without American intervention at the top level. Secretary of State Henry Kissinger after the 1973 war and President Jimmy Carter at Camp David in 1978 justly earned places in history for efforts that led to Middle East accords. Secretary of State James A. Baker III's great triumph was to start the current peace process, bringing the warring parties together at Madrid.

Though Clinton earned credits for brokering the Wye accord in 1997, the deal covered only a fraction of the principles adopted at Oslo in 1995. Though negotiated without American intervention, Oslo's execution had been stalled until Clinton stepped in. The job remains unfinished, however. In the absence of U.S. involvement, Oslo will surely fade to a footnote in history.

When Ehud Barak, Israel's newly elected prime minister, visited Washington this summer, he urged Clinton to keep his hands off impending peace talks, arguing that the parties could handle them alone. In agreeing, Clinton made a great mistake. Given the glacial pace of the talks, so did Barak. Neither he nor his counterpart, the Palestinians' Yasser Arafat, is certain now of the degree of Clinton's commitment to a final peace.

It is true that Clinton sent Secretary of State Madeleine Albright to the Middle East a few months ago to encourage the parties. She came home without achieving any results.

It is also true that Clinton himself traveled to Oslo recently to meet with Barak and Arafat. But the two adversaries did no more than shake hands and promise good will in dealing with each other. The president neither requested nor received commitments on the "final status" negotiations on which they are embarked. The meeting was ceremonial, nothing more.

To be sure, Clinton, as president, is too heavily burdened to mediate the Israeli-Palestinian conflict alone. It took Jimmy Carter two weeks, a huge amount of time, to talk Israel and Egypt into an agreement at Camp David. Resolving Israel's differences with the Palestinians, infinitely more complicated, will take far longer. Though Clinton may join in the last stages to clean up loose ends, he must delegate to a top-level figure the authority, extending for months, to represent him at Barak-Arafat talks.

The president does not currently have such a representative. He uses the State Department's amiable Dennis Ross and his assistant, Aaron Miller, to shadow the peace process. Both are estimable, middle-level diplomats, without real powers. Moreover, they have been around since early in the Bush presidency, and by now neither has anything new to bring to the negotiations. Israelis and Arabs alike admit to having grown a bit weary of them.

If Clinton is to be serious, he must find an American who speaks not for the State Department bureaucracy but for the presidency itself. That is the role that former senator George Mitchell has played in the long, arduous negotiations aimed at producing a peace in Northern Ireland.

A few candidates come readily to mind. One is President Carter, who still seems to have the energy, patience and the zest for such a challenge. His earlier differences with Clinton need not stand in the way of his appointment.

Another is former secretary Baker. A stern, dogged advocate, Baker would make a first-rate intermediary, if he and Clinton could, in the national interest, lay aside their partisan differences.

Turning to the Mitchell model, the president might well select a top-level figure without regional experience. Walter Mondale comes to mind as a distinguished public servant, a former senator, vice president, presidential candidate and ambassador. If a man of such stature walked into a room as vicar of the president, the Israeli and Palestinian delegations, even Barak and Arafat themselves, could not fail to listen very closely to him.

No one--not the Lord himself--would find it easy to reconcile the huge differences that separate Israelis and Palestinians. The "red lines" that Barak and Arafat proclaim are far apart, and the chances of their reaching an accord on their own are slim. If Clinton wants a settlement before his term expires, he will have to turn the heat way up. Having a personal representative esteemed by all would be the best place to begin.

Milton Viorst, a Washington writer, has been covering the issue of Middle East peace for 25 years.