Beirut — Keeping up with Arab diplomacy has become a dizzying process, as both moderates and militants scramble to consolidate positions on the United States Middle East peace initiative.
Among the past week's major moves:
* Saudi Arabian officials have been involved in intense negotiations with Iraq, Syria, and Jordan at the highest levels, both in Riyadh and during shuttle diplomacy by Crown Prince Abdullah.
* Jordan's King Hussein has paid calls on Saudi Arabia and Iraq.
* The Syrian foreign minister has visited five Gulf states, carrying messages from President Hafez Assad.
* Branches of the Palestine Liberation Organization have met in Libya, Syria, and North Yemen, while chairman Yasser Arafat seems to wander everywhere.
These moves have come as the Arab world is questioning the level of commitment by the Reagan administration to a genuine Middle East peace.
Moderates, led by Saudi Arabia, are lobbying for the Arab world to give the US more time. Militants, led by Syria, argue that a firmer line must be taken on the Reagan plan, leaving the door open to alternatives.
Meanwhile, the PLO - as usual - is showing cracks that reflect the ideological and tactical divisions in the Arab world.
The Saudis have led the way on two fronts. They are trying to heal splits within the 21-nation Arab bloc that in the past have prevented joint action on the bigger issues. And they are trying to pull together an alliance of parties interested in negotiating on the basis of the Reagan plan that would be credible enough to outweigh dissidents. A tentative willingness has been expressed, according to Western diplomats, by Iraq, Jordan, Saudi Arabia, Algeria, and PLO moderates led by Mr. Arafat.
The biggest diversion has been the 28-month-old Gulf war and the resultant split of alliances, particularly between Iraq and Syria, two mainstream countries in any final settlement.
King Fahd began mediating between the two rival Baathist regimes last September, but no progress was evident until Gulf newspapers reported this week that the Saudi shuttling had ''produced positive results to be announced shortly.''
King Fahd has also dispatched emissaries to help repair damage in relations between the Syrian President and Mr. Arafat over Arab diplomatic strategy.
The Syrian regime has been out front in expressing doubt about the Reagan plan, both for selfish reasons involving the uncertain status of its former Golan Heights annexed by Israel in 1981, and for diplomatic reasons based on doubt about US willingness or ability to pressure the Israelis.
Syrian displeasure has heightened as King Hussein and Mr. Arafat appear to be making progress on a joint approach to the US plan. Unconfirmed reports speak of agreement on a five-man team of non-PLO Palestinians to join a Jordanian team in talks with the US.
The Assad government has been pressuring the PLO hard-liners as a means of reining in Mr. Arafat, with some success. At the end of a weekend meeting in Libya five of the eight factions issued the so-called ''Tripoli declaration.''
It announced ''categoric rejection of recognition of, or mediation and peace with the expansionist Zionist entity (Israel).'' It rejected any other party but the PLO negotiating on behalf of the Palestinians. It even denounced the Arab peace plan approved by Arafat at the Moroccan summit last September, charging ''Arab reactionaries'' had ''dragged the Arab countries and the PLO into capitulationist schemes.''
Though many such statements have traditionally been dismissed as radical Arab rhetoric, made under pressure of the host country or as posturing, the communique did underline the growing rift between supporters and opponents of Mr. Arafat's recent moves.
Syria and Libya have shown signs of trying to revive the militant ''Steadfastness and Confrontation Front,'' which evaporated during the Israeli invasion. Together they have argued behind the scenes that the Reagan plan amounts to diplomatic trickery, since the US had not come through with any reassuring signs of commitment.
Instead, they point out, that US aid to Israel has increased, there is no halt to new Israeli settlement plans, and talks on Lebanon continue to be bogged down, preventing progress on a broader peace.
Even the moderates in favor of giving the Reagan plan a try have been stymied by this argument. While they stress that the Arab world for once must not be seen to be responsible for failure of a peace plan, they also know that the US must give a stronger signal of its commitment before the cautious Arabs can in turn commit themselves.