Syria's expulsion of Palestine Liberation Organization Chairman Yasser Arafat appears to be part of a move by President Hafez Assad to make Syria a dominant force in the Arab world and pivotal in any negotiations to resolve tensions in the Middle East, U.S. officials said yesterday.

The officials said that if Syria wins control over major elements of the PLO it would strengthen greatly Assad's effort to serve notice that Syrian cooperation is essential not only to resolution of the Lebanon crisis but also the broader Arab-Israeli conflict.

What remains unclear, the officials stressed, is whether Assad would use this increased power to remain "rejectionist" or to gain maximum leverage in future negotiations with the United States, Israel and Lebanon.

The Syrian move against Arafat came at a time when the Reagan administration, aware that time is running out for its effort to get Israeli, Syrian and PLO forces out of Lebanon, is trying again to induce Syria to cooperate with the Lebanese-Israeli peace accord.

President Reagan's two special Mideast envoys, Philip C. Habib and Morris Draper, were scheduled to return to the area yesterday to explore the chances for opening a U.S.-Syrian dialogue.

Although the Syrians have rejected a Habib visit to Damascus, the United States is hopeful that Assad will receive Draper, Deputy Secretary of State Kenneth W. Dam or Nicholas Veliotes, assistant secretary for Mideast affairs.

In addition, Secretary of State George P. Shultz, currently traveling in the Far East, is understood to be willing to visit Damascus during his return home in early July if the Syrians give any sign of willingness to talk seriously.

These U.S. moves had been predicated on the assumption that Assad can be convinced that his best interests lie in an arrangement that would make Lebanon a neutral buffer between Syria and Israel and ease the chances of a major new war between the two countries.

But some U.S. officials, who declined to be identified, said Syria's support of an internal PLO mutiny against Arafat could force the United States to reexamine all of its assumptions about how to deal with him.

According to this view, if Assad emerges as the real power behind those cohesive PLO elements that remain in Syria and Lebanon he can use them to perpetuate a de facto partition of Lebanon for as long as he wants.

If Syria and the PLO stand pat, Israel, suffering a heavy casualty rate, would be under increasing pressure to regroup its forces in the extreme south of Lebanon or pull out completely.

Similarly, if Assad has the main body of the PLO under his thumb he would be in position to tell Washington that its hopes for a comprehensive Mideast solution encompassing the Palestinians can only be realized by dealing with him rather than such traditional U.S. allies as Saudi Arabia, Jordan or Egypt.

If this scenario is correct, Assad's aim is to make Syria indispensible to progress on all fronts in the Middle East.

Whether he will achieve that goal is unclear, the officials said.

But if he does, they added, he could confront the United States with the unenviable choice of seeing the region kept in perpetual turmoil or trying to accommodate Syrian demands for far-reaching concessions from Lebanon and Israel.