Saudi Arabia's considerable prestige is on the line at the 12th all-Arab summit taking place this week among the bougainvillea and palm gardens of Morocco's ancient city of Fez.
The Saudis are negotiating intensely behind the scenes to win support for their Mideast peace plan, the central issue at the summit, so that it can be placed on the agenda for consideration. If the plan is accepted, and eventually adopted, it appears likely to carry some amendments to appease the more radical Arab heads of state.
The key provision of the plan calls for Israel to withdraw from land it captured in 1967 and implies that Israel's existence will be recognized in return by the Arab states.
It would be a historic first if the often-quarrelsome Arab League members agree on a joint Mideast strategy - and a stunning success for the Saudis, who are riding the crest of a year's worth of diplomatic achievement. So far the Saudis:
* Diffused Syrian-Jordanian border tension exactly one year ago.
* Cooled the infighting in Lebanon.
* Helped negotiate an indirect cease-fire between Israel and the PLO.
* Lined up the Organization of Petroleum Exporting Countries (OPEC) behind Saudi price policy.
* Indirectly won a tough US congressional fight recently over the sale of AWACS surveillance planes and other military equipment to the desert kingdom.
''I tell you,'' says a veteran Arab commentator, ''if the Saudis win the (Crown Prince) Fahd plan, there will be no doubt Saudi Arabia is the leader'' of the Arab world.
But Arab diplomacy can be as confounding as the streets of Fez's celebrated medina, by far the most intricate and colorful in the Arab world. Though the Saudis are in a strong position going into the Nov. 25 opening of the Arab summit, a meeting among foreign ministers, now in progress, is revealing equally strong Arab opposition:
1. Iraq is known to be upset that the Saudis are bidding for the leadership of the Arab world. Since Egypt was ostracized for its peace treaty with Israel, Iraq itself has aspired to this role. But the war with Iran has tied down Iraq's resources and political flexibility. Informed observers say Iraq could cause problems for the Saudi peace plan.