MADRID, Spain -- He entered the Hall of Columns late and almost furtively, taking a chair behind his silent brethren from the Persian Gulf states.
But the presence in traditional desert robes of Prince Bandar bin Sultan bin Abulaziz al-Saud, Saudi Arabia's ambassador to Washington and nephew and close confidant of King Fahd, caused an immediate stir at the Middle East peace conference.
It put the stamp of approval of the king, a premier source of financial aid throughout the Arab world and a pillar of Islam as custodian of its two holiest shrines, on the historic face-to-face meeting of Arabs and Israelis.
The 42-year-old prince's visibility marked an increasingly open role in Middle East diplomacy for a government known for lavish but secret consensus-building.
Prince Bandar's behind-the-scenes arm-twisting was pivotal in finally getting Arab negotiators to sit down with Israelis Sunday.
In his closing comments at the conference, Secretary of State James A. Baker III paid tribute "to King Fahd of Saudi Arabia, who demonstrated by word and deed that new opportunities for Arab-Israeli peace existed after the gulf war and who personified this new approach in the Arab world."
The new role results in large measure from the close ties, deepened during the Persian Gulf crisis and the war that followed, between Mr. Baker and the man popularly known in Western circles as Bandar.
Those ties, and Prince Bandar's influence with his uncle, the king -- especially in obtaining an invitation for U.S. intervention in Saudi Arabia -- give Mr. Baker valuable cards to play as the peace process unfolds.
The Saudis' symbolic weight and vast oil wealth are expected to be a major incentive for Arab states to cooperate in planned but unscheduledtalks with Israel on regional issues.
With the decline of the Soviet Union as patron of poorer, radical Arab states such as Syria, the Saudis can exert even greater economic leverage because of the diminishing number of places for those states to turn.
Prince Bandar, a flamboyant diplomat with a zest for intrigue and skills as public speaker and stand-up comic, is both the main conduit between Washington and Riyadh and a private regional emissary for the king, who sent him to Damascus, the Syrian capital, before the Madrid conference opened.
He has played an active behind-the-scenes role since Mr. Baker's first peace-process shuttle eight months ago.
"Since the gulf war, [the Saudis] realized faster than most that things had changed and were willing to look at things in a new light," a U.S. official here said.
U.S. and Saudi interests coincided when the kingdom cut off aid to the Palestine Liberation Organization, which had alienated the gulf states with its support for Iraqi President Saddam Hussein.
That financial club helped sideline the Tunisia-based PLO leadership, allowing the United States to forge a public relationship with moderate and respected West Bank leaders less objectionable to Israel.
At a moment timed by Mr. Baker for maximum impact, the Gulf Cooperation Council, in a statement bearing the Saudi insignia, announced it would send an observer to the peace conference (( and that its member countries would participate individually in multilateral talks with Israel.
At another propitious moment, the Saudis endorsed Egyptian President Hosni Mubarak's proposal to end the Arab boycott of Israel if that country would suspend building settlements in the occupied West Bank and Gaza Strip. Israel refused.
After returning to Washington with agreement from Israel, Syria, Jordan and the Palestinians to attend the Madrid conference, Mr. Baker asked Prince Bandar to attend. King Fahd approved.
In the days leading up to Wednesday's formal opening of the talks, theprince consulted with Margaret D. Tutwiler, assistant secretary of state for public affairs and one of the most important figures in planning the conference.
After Mr. Baker's arrival, Prince Bandar spent hours with the secretary of state and his aides and, along with Egyptian Foreign Minister Amr Moussa, became a key intermediary with other Arab governments.
Their help was crucial in the high-stakes wrangling, played out in luxurious suites between Arab heads of state, during the 48 hours between the conference and the scheduled opening of bilateral talks.
The Palestinians wanted the talks to proceed, and King Hussein of Jordan later gave the go-ahead for the Jordanians.
But Syria and Israel were locked in a dispute over whether to hold a first meeting simply on procedural issues.
Arabs also saw Israel hardening its position on conducting subsequent bilateral talks in the Middle East, which would give it de facto Arab recognition.
Mr. Baker met with Prince Bandar and Mr. Moussa for 40 minutes Friday afternoon.
The two Arab diplomats then went to work on the other Arab delegations, with the aim of bringing Syria on board. Mr. Baker was to deal with the Israelis.
A meeting of Arab delegations, along with contacts between Prince Bandar, Mr. Moussa and the Americans, continued until 3 a.m. Saturday, an Arab diplomat said.
By late Friday, Syrian Foreign Minister Farouk al-Sharaa still planned to return to Damascus the next day, leaving Sunday's direct Israeli-Syrian talks in doubt.
But by Saturday, Mr. Mubarak and King Fahd had "weighed in heavily" with Syrian President Hafez el Assad, who ordered his foreign minister to stay in Madrid.
Mr. Baker said Friday that more confidence-building measures were needed from the Arabs and the Israelis, but his praise for King Fahd seemed to exempt Saudi Arabia.
For now, the Saudis, along with other Arab states, want to see steps by Israel, particularly progress in negotiations, before making concessions. They also resent the bombardment of southern Lebanon just before the bilateral talks began.
But Mr. Baker is likely to hold additional Saudi cards awaiting for the right time to play them.