Will President Reagan support the 35-year-old US commitment to a compromise peace in the Middle East, based on a sharing of Palestine? Or must the United States adjust to a ''winner-take-all'' Israel?
These questions, says Harold H. Saunders, go to the heart of decisions that must be worked out, not only by the US, but by Israel and Jordan as well.
Israel and the US, in Dr. Saunders's view, ''no longer are operating from common premises. When paths diverge, as they do now, we must discuss together - where are we going?''
The Israeli government, meanwhile, appears to be shutting the door on a compromise peace by ensuring de facto Jewish control of the West Bank and Gaza.
This policy, says Saunders, sets the stage for ''another generation of Arab-Jewish conflict,'' with the possibility down the road of nuclear arms being introduced to the Middle East.
As assistant secretary of state for the Near East and South Asia, Dr. Saunders was one of the few Americans closeted with President Carter, Israeli Prime Minister Menachem Begin, and the late Egyptian President Anwar Sadat during the Camp David negotiations, which led to Israeli-Egyptian peace.
''For 35 years,'' says Saunders, now with the American Enterprise Institute (AEI) in Washington, ''the US has supported the security of both Israel and Jordan, but never on a winner-take-all basis.''
Rather, in his view, US policy since the creation of Israel has been ''committed to a just peace, a compromise peace, based on a sharing of the land between Jews and Arabs.''
Intimately involved in what is going on - and facing extremely difficult choices - are Mr. Reagan, the Begin government in Jerusalem, and King Hussein of Jordan.
''Israel,'' says Saunders, ''through the Begin-Sharon leadership, is making a historic choice about the future shape of the Zionist state.''
What will be done with the 1.7 million Arabs living in the occupied territories? If they are given citizenship, Israel becomes binational, with a 40 percent Arab minority.
Suppression of their rights, on the other hand, condemns Israelis to future military control over a restless and hostile people, a choice repugnant to most Israelis.
For King Hussein, powerless on his own to sway Israeli policy, the choices are equally difficult.
Either, Saunders says, he must play a negotiating role in the hope - with strong US backing - of retaining some Arab authority over the West Bank and Gaza , ''or he foresees the East Bank becoming the future Republic of Palestine.''
The East Bank refers to Jordan proper, the territory east of the Jordan River carved by Britain out of its Palestine mandate after World War I and bequeathed to Hussein's grandfather, Abdullah.
A majority of Jordan's citizens are of Palestinian origin, refugees from land that now belongs to Israel. They were given Jordanian citizenship by Abdullah after the 1948 Arab-Israeli war. Relations often have been strained between the new citizens and the original Transjordanian Arabs, many of whom are of Bedouin stock.
''What Hussein and the Jordanians really fear,'' says Judith Kipper, a Middle East expert with the AEI, ''is an influx of West Bankers - many of whom (already) have bought apartments on the East Bank, in case (West Bank) negotiations collapse.''
Hussein, experts say, perceives the advantage lying with Israel, which has been steadily increasing what is in effect the permanent settlement of Jews on the West Bank.
Unable on his own to halt this tide of events, the Jordanian King looks to the US for support, against the background of longtime American insistence on a compromise peace.
President Reagan, meeting with reporters Feb. 23, spoke of the need to provide ''something in the nature of a homeland'' for displaced Palestinians, short of ''creating a nation.''
The President's concept, outlined in his Middle East initiative of last September, calls for a Palestinian entity on the West Bank and Gaza, linked in some fashion to Jordan.
Such an option, however, dwindles in the face of the Begin-Sharon settlement policy, to which the new Israeli defense minister, Moshe Arens, also subscribes.
Few observers doubt Mr. Reagan's sincerity. Most applaud his Middle East peace initiative. But the President has not - or is unable to - put effective pressure on Israel to halt its settlement plans.
In these circumstances, said one specialist, ''King Hussein sees the US openly or tacitly supporting Israeli policy.''
Experts generally doubt that Reagan can deflect Begin from a West Bank policy that appears to have wide support within Israel. ''Overall,'' said Ms. Kipper, just back from an extended Middle East tour, ''the interest in Israel in hanging onto those territories is very, very great.''
That, says Dr. Saunders, is why people ask: ''Will the US put its weight behind the historic compromise - sharing the land of Palestine - or behind Israel taking all?''
Meanwhile, he concludes, ''time is changing the shape of the Palestine problem.''