President Reagan appears to be returning to the mainstream of American Middle East policy with a new drive to resolve the Palestinian issue. But the effort is likely to bring the US into conflict with Israel.
As described by administration officials, the essentials of the new ''American plan'' would urge, in return for Arab recognition of Israel, Israeli withdrawal to pre-1967 borders, with possible minor modifications to be made in those borders for purposes of Israeli defense.
At this writing, President Reagan was expected to make a statement Wednesday night outlining the administration's long-awaited approach to the Palestinian issue.
Officials here confirmed an Israeli Radio report that Mr. Reagan sent a letter to Israeli Prime Minister Menachem Begin containing American proposals and calling, among other things, for a freeze on Israeli settlements on the largely Arab-populated West Bank of the Jordan River and in Gaza.
The letter also apparently reaffirms the American preference for a Palestinian entity on the West Bank and Gaza, which would be linked in some form of federation with the Kingdom of Jordan. These are all ideas which were a standard part of President Carter's approach to the Palestinian issue. Officials denied Israeli allegations that they would mark a departure from the US-sponsored Camp David agreements of 1978.
The conflict with Israel is likely to come over interpretations of the Camp David accords, over the Reagan call for a settlements freeze, and over American attempts to strengthen the powers of the Palestinian self-governing authority which is called for in the Camp David agreements. As the Israelis see it, that authority should be limited to certain administrative functions, thus leaving essential control of the West Bank and Gaza in Israeli hands.
As some members of the Begin government see it, full ties between Jordan and the West Bank, as proposed by the Reagan administration, might only set the stage for the creation of a Palestinian state, which Israel opposes. Israeli Defense Minister Ariel Sharon and Foreign Minister Yitzhak Shamir argue that Jordan, and not the Israeli-occupied West Bank, should be the future homeland for displaced Palestinians.
President Reagan's new initiative is clearly aimed in part at assuring Jordan , and other Arab nations, that the US does not agree with this view. The President wants to demonstrate to America's Arab friends, in the wake of the Lebanon crisis, that it has not lost sight of the volatile Palestinian issue. Jordan feels extremely vulnerable to possible Israeli pressure at the moment.
A White House official said that President Reagan was also brought to his decision to make public his views on Middle East peace by a series of Israeli actions and by the realization that only the United States - as demonstrated by the recent US-sponsored Beirut negotiations - had the power to nudge all the parties toward a settlement of the Palestinian issue.
''Ronald Reagan has become familiar with the Camp David accords,'' said a White House official. ''And he has observed Israeli actions that have not been helpful - the West Bank settlements, the annexation of the Golan Heights, the raid on the Iraqi nuclear reactor, and the Lebanon invasion. . . . None of these have been helpful, to say the least, in resolving the Palestinian issue.''
At the same time, the official said that the President was not threatening Israel. He said that the Reagan move amounted to a high-level diplomatic initiative, which could at some point involve the appointment of a high-level American negotiator.
Until recently, President Reagan had projected an ambivalent attitude when it came to what were regarded by many experts here as essentials of the Camp David accords and of earlier United Nations' resolutions, agreed to by the United States, concerning the Arab-Israeli conflict.
The President's attitude toward the West Bank settlements, for example, had been at first quite tolerant of the Israeli position. He had argued, in contrast with previous administrations' positions, that the settlements were ''not illegal'' and ought to be decided upon in negotiations involving the Israelis. That was fine with the Begin government, it seemed, and Israel went ahead with the settlements. On the Lebanon invasion, the Regan administration seemed to agree with Israel's objectives, if not its tactics.
The President is still described as strongly supportive of Israel and skeptical of the usefulness of bringing the Palestine Liberation Organization (PLO) into any future settlement.
''There are no new ideas,'' said another official. ''But there is a determination to get something done with the old ideas.''