President Carter's dramatic Middle East initiative neared its end tonight with no plan for signing or initialing an Egyptian-Israeli peace treaty and with unresolved issues still remaining.

White House officials, decidedly downcast, announced that the president and his entourage will return to Washington Tuesday without the accord and with no agreed procedures for continuing the attempts to get one.

The developments, unless Carter can reverse them with a last-minute success that no one here expects, seemed to constitute a setback to hopes for swift progress toward putting the Camp David accords into practice, and to Carter personally after his investment of time and prestige in coming to the Middle East for on-the-spot negotiations.

There is no plan for a three-way summit between Carter, Israeli Prime Minister Menachem Begin and Egyptian President Anwar Sadat, presidential press secretary Jody Powell said. And there is no plan even for Secretary of State Cyrus Vance to remain in th Middle East shuttling back and forth between Cairo and Jerusalem trying to work out the few differences that remain, he added.

Instead, Carter has scheduled one last breakfast with Begin. Then he and his high-level advisers will fly to Cairo for a brief airport meeting, where he will review with the Egyptian president "his discussions here in Israel," Powell said.

Then the entire party plans to reboard Air Force One and return to Washington.

Administration officials do not ruel out the possibility that there might be a last-minute change of position by either side -- by Begin at breakfast or by Sadat at the airport -- and that Carter's dramatic personal effort might somehow be given new life. But the Carter officials gave no indication that they believe that will happen.

Carter had been scheduled to leave for Washington today. But he postponed his departure so that he and his advisers could continue their talks with the Israelis.

Egypt and Israel have narrowed their differences down to just a few. It was learned that the differences are, in order of severity:

The Gaza Strip, where the Egyptians would like Israel to act first on granting autonomy to Palestinians and where there is also dispute on just how extensive a role Egypt could have in the process; the Sinai oil wells, where Israel is seeking guarantees of future sales; an exchange of ambassadors, in which Israel wants top-level diplomatic recognition and Egypt proposes lower representation.

Differences also exist in the three proposals made a week ago by Carter and which were approved by the Israeli Cabinet. But these are believed by U.S. officials to be comparatively minor.

The question whether there should be a target date for elections in Gaza and the West Bank, or Just for completing arrangements for the elections, has been decided in favor of the completion of arrangements. The only difference is whether the language that follows will call for elections "as soon as possible" or "expeditiously," officials said.

A more serious problem has surfaced over a procedural question on the Israeli side. Begin has told Carter that he could not sign, or even initial any agreement until it has first been approved by the Knesset, the Israeli parliament. U.S. officials had been told previously by Israel that Knesset approval would be required at some point, but it was apparently never put to them quite so explicitly.

The requirement of prior Knesset approval could make completion of an agreement more difficult for Sadat. Israeli sources say it also is possible that the Knesset could approve some parts of the agreement and reject others.

When asked whether a three-way summit is an option that the president is considering, Powell replied, "So far as I know, there is no one who believes, under the present circumstances, that that is a worthwhile course" to follow.

The possibility -- raised by the Israelis -- that the draft treaty and its compromise proposals could be submitted to the full Israeli parliament for revision and piecemeal approval appeared to be one of the upsetting factors in the negotations.

Some officials of the Israeli and U.S. governments have maintained that given the political climate in the parliament here and the emotionalism surrounding the unresolved issues, it is unlikely that the treaty could survive a debate in the Knesset.

The original Camp David framework for peace was approved last fall largely because the opposition Labor alignment provided the swing vote for Begin. But the Labor Party, Along with conservative factions of parliament, now is vocally critical of the autonomy plan for the West Bank and Gaza Strip because its members view the proposal as inevitably leading to a Palestinian state.

Earlier in the day, Carter signaled the downturn in the talks in a speech to the Knesset, in which he said the people of Israel and Egypt are ready for peace but that "the leaders have not yet proven that we are also ready for peace enough to take a chance."

He acknowledged the volatile character of the talks so far, saying in his opening remarks," I have discarded a speech of despair, discarded a speech of glad tidings and celebration, and decided to deliver a speech of concern and caution and hope."

While pledging to pesevere in the peace initiative, the president suggested the possibility of failure, saying: "But with or without a peace treaty, the United States will always be on Israel's side.

"Despite our unflagging determination, despite the extraordinary progress of the last six months, we still fall short," Carter said.

When it was Begin's turn to address the parliament, opponents of the prime minister's peace policy turned the session into a shouting and heckling match, while Carter looked on with alternate expressions of embarrassment, amusement and displeasure.

Begin was interrupted dozens of times as members shouted criticism from the floor, so much so that the session dragged on 45 minutes longer than scheduled as the prime minister tried to complete his speech.

Opponents were split between ultranationalist members of Begin's own Likud bloc, who feel the peace treaty is a sellout conducted under American pressure, and representatives of the small Communist bloc.

While no visiting head of government has witnessed such a prolonged outburst of heckling in the Knesset before, Begin is used to such treatment. As he often does, he appeared to enjoy the shouting as a demonstration of Israeli democracy and informality.

The most persistant of the hecklers was Geula Cohen, a long-time Herut ally of Begin's, who finally was ejected from the chamber with the voted approval of a majority of the members. Screaming from her seat at Begin, Cohen appealed for release of several members of the ultranationalist Gush Emunim arrested during the past two days during protests against the Carter visit.

"I will not let you speak, Mr. Prime Minister. Go and visit the people who were arrested when Carter came to visit. It is a police state. I want to be allowed to speak," Cohen shouted, until two matrons forced her to leave the chamber.

At one point, Begin said to Carter: "Mr. President, before you is the Israeli Knesset. It contains various parties and various views. As you see, our democracy is beautiful. No Knesset members, from any faction, interrupted your address with even one word."

Begin added: "But they have interrupted me, and I want to say that this is perfectly legitimate to interrupt the prime minister in his speech in this house."

While he occasionally smiled at the exchanged barbs, Carter for the most part sat stony-faced, staring straight ahead, without paying any attention to the political theater in front of him, which was accompanied by noisy gavel-pounding by Knesset speaker Yitzhak Shamir.

In his own speech, Begin made it clear that he will not initial or sign a treaty until it has been approved by the Knesset. While acknowledging that the parliament normally ratifies treaties after they have been approved by the Cabinet and signed by the prime minister, Begin said, "The problem is not usual."

He also said Israel "insists and shall continue to insist" on an exchange of ambassadors, one of the major sticking points remaining in the faltering peace talks.

For the Israeli government and the United States delegation, today's negotiations blended into yesterday's marathon session. The Cabinet met throughout the night until nearly daybreak debating Israel's position on compromise changes demanded by Sadat.

Finally, at 5:20 a.m., a visibly weary Begin stepped out of the prime minister's office and told reporters that the government has made "important decisions" that he said he hoped would hasten a treaty signing, and that they were to be conveyed to the Americans.

Actually, as the Cabinet debated and voted on the outstanding issues throughout the night, the decisions were being relayed to Vance, whom Carter had instruted to make himself available until the Cabinet finished.

To enable the ministers to get some rest, a scheduled meeting with Carter was postponed from 8 a.m. to 10 a.m., when the president drove to Begin's office and met with the Cabinet.

The disputes in the remaining issues are:

Sinai oil wells -- Israel will be handing them back to Egypt, and Egypt agreed at Camp David that it would consider Israeli requests to buy oil on the same basis as any other country. Israel is demanding the right to purchase all the oil the wells now produce, and all the oil they can produce in the future. But Egypt has refused to consider Sinai oil sales to Israel until after relations with Israel are normalized. Carter did not present a compromise plan on oil.

Exchange of ambassadors -- Israel considers an exchange of ambassadors important to show the level of normalized relations that is to be achieved. Egypt is insisting on an exchange of diplomats at a lesser rank, at least at the outset.

Gaza -- Egypt, expecting that Israel will have problems with Jordan and the Palestinians on negotiating autonomy with the West Bank, wants Israel to show good faith by beginning autonomy in the Gaza Strip. If autonomy is begun there first, there is a question whether Egyptian officials would have a role in administering the process.