President Carter's strategy in going to the Middle East this week involves even more than the momentous Egyptian-Israeli peace treaty that he may finally be close to achieving.He will also be seeking to stem a series of foreign policy reverses that now threaten to undermine the American position all across that region.

Carter has accepted an enormous foreign policy risk in trying to build on U.S. failure in Iran, new signs of leadership weakness in Saudi Arabia and war in the Yemens.

But the White House appears to have concluded that the turmoil of the region and the perception of increasing Soviet probing and gains along the Persian Gulf and in the Arabian peninsula also provide an opportunity to get Egypt and Israel to consummate the treaty that has been clear in outline for months.

Details of the new U.S. proposals that Carter has made to break the deadlock are still secret. But the White House actions and statements in recent days have left the clear impression that the administration has decided to press Egyptian President Anwar Sadat to sign the treaty now as the first essential step in alting what Carter evidently fears could be a strategic shift of the region away from American influence.

The Egyptians, in effect, would be asked to accept something less on Palestinian rights in the West Bank and Gaza Strip territories than they have been demanding. In return, Sadat is likely to be offered more than now exists in the way of an American role in protecting the region militarily from "Soviet penetration and subversion."

This trade-off would clearly please the Isaelis, who can be almost certain that any increased U.S. military involvement with Arab states would have to be balanced by equivalent increases for Israel.

Diplomats generally sympathetic to Carter's aims in the Middle East were stunned by his decision to place himself squarely in the middle of the negotiating process in the dramatic "jetliner diplomacy" style pioneered by former secretary of state Henry A. Kissinger.

"It is extremely risky -- to Europeans, even a little crazy," said one West European diplomat. "There is no fallback position if this fails. But you have to admire his audacity and his sincerity in trying to get a settlement."

One set of dangers appears to lie precisely in the promise of even deeper U.S. involvement in the region that Carter's presence as negotiator implies. The number of concessions each side can extract from Washington for signing the treaty is probably at its peak.

For some Arab diplomats, that danger is overshadowed by the potential for confrontation within the Arab world over an agreement that would be seen as having secured less for the Palestinians than Sadat has repeatedly said he would accept.

The trip, evidently being undertaken without any assurances that Sadat will agree to the deal Carter has worked out with Israel, put Saudi Arabia on the spot at a time of significant internal strains in the Saudi royal family and of peturbed relations between Washington and Riyadh.

Carter's decision to accept these risks at least implicity is a measure of the urgency the White House feels in dealing with the rapidly shifting Middle East equation. At one level, the Carter administration appears prepared to accept a period of some estrangement with the Saudis and with Jordan's King Hussein if that is the price for an Egyptian-Israeli treaty now.

The Egyptian-Israeli talks on a treaty stalled in November, primarily because of Israeli concern that the Carter administration was planning to push hard for Palestinian local rights in the second set of negotiations that are to follow the signing of the bilateral peace agreement.

Four events outside the negotiating process since that deadlock developed have helped push Carter, Sadat and Israel's Prime Minister Menachem Begin toward this week's long-distance negotiating encounter.

The events have helped alter the administration's priorities, which now seem to assign a higher place to the Soviet problem than the Palestinian problem, and they will be stressed by the administration in the president's audacious roll of the dice in Cairo and Jerusalem this week. They are:

Revolution in Iran. The overthrow of the shah by a regime that is avowedly anti-Israeli and more neutralist in global politics is still shaking the policy assumptions of all three leaders, who had major investments in the shah.

In the White House view, Israel has shifted from seeing the shah's downfall as cause for digging in its heels on the tals to seeing it as reason for reducing the risk of new confrontation with the United States. Sadat's regional anti-Soviet strategy is also significantly weakened.

Last week's well-planned and well-executed invasion of North Yemen's border regions by the Marxist government of South Yemen. The United States is urgently rushing new weapons to North Yemen, while the Soviet Union appears to have begun a resupply effort for the Aden forces. A major escalation is likely.

Administration officials are streessing to Saudi Arabia and Egypt that Soviet military advisers in South Yemen are doing nothing to restrain the South Yemeni assault, and may be encouraging it.

A mounting loss of confidence in Saudi leadership by Sadat and the Carter administration. Saudi support for Sadat has been week to non-existent since last November when Crown Prince Fahd got badly outmaneuvered at the Arab summit in Baghdad.

Arab pressure on Sadat to pull out of the treaty negotiations has again intensified since the Saudi royal family decided not to send Fahd on an official visit to Washington this month as scheduled. The administration fears that further delay in a time of weak Saudi leadership on this issue will cause fragmentation and growing radicalization of the Arab moderates who had been counted on to support Sadat eventually.

Secretary of Defense Harold Brown's tour of the Middle East last month. That trip has resulted in increased visits to the region by U.S. naval vessels and touched off discussion with the Saudis of a joint military working group. The Saudis shied away from endorsing a direct American can role in regional security, an idea that Brown let them know he was prepared to discuss.

Israel made a point of taking Brown and his party to two air bases in the Sinai peninsula that are due to be returned to Egypt under the treaty. The Israelis signaled to Brown they would feel much more comfortable in having an American presence on the bases to defend "the free world." U.S. officials report Brown gave a deliberately ambiguous response on that possibility.

These strategic considerations in the Middle East have eclipsed the Palestinian autonomy scheme that was the crux of the dispute between the Egyptians and the Israelis over the final points of the peace treaty.

The diplomatic arguments over link-age and target dates were in fact largely about the powers and responsibilities that the Israeli military government would cede to the Palestinian administrative councils to be elected on theWest Bank and in the Gaza Strip under the second set of Camp David agreements.

But it now seems that the Carter administration is far more concerned about immediately restoring some balance in what President Carter's national security affairs adviser, Zbigniew Brzezinski, has called "the arc of crisis" that centers on the Persian Gulf and the Arabian peninsula.