Beirut ? As Druze warlord Walid Jumblatt serves a sumptuous dinner to a gathering of Lebanese notables here, the talk around the table is about who will fill the power vacuum in the region if America reaches a nuclear deal with Iran — and accelerates what’s seen as a U.S. withdrawal from the Middle East.

That’s the kind of existential anxiety I encountered across the region recently, as negotiations between Iran and the “P5+1” group moved toward a climax. This is a deal that would alter the power dynamics that have shaped the Middle East since the Iranian revolution of 1979, and many regional players who favor the status quo, especially Israel and Saudi Arabia, are worried.

Despite the uproar since talks broke off last weekend, the process of negotiation seems about where it should be — at least from the U.S. standpoint. Iran has been asked to accept a freeze on its nuclear program in return for a limited release of its frozen assets. The Iranians, upset that the deal demands too many concessions without granting them a “right” to enrich uranium, have balked. Meanwhile the vise of sanctions continues to squeeze their economy.

If Iran accepts the deal, it would be a strong first step toward a final agreement to halt its nuclear program. During this initial phase, the sanctions framework would remain in place and Iran would allow greater inspection of facilities. Given Iranian resistance, it’s hard to see this as the “deal of the century” for Tehran or a “fool’s game” for the West, as Israeli Prime Minister Benjamin Netanyahu and French Foreign Minister Laurent Fabius have charged, respectively.

Let’s give Netanyahu and Fabius credit for playing the “bad diplomat” role to gain maximum leverage. They’ve created a dynamic where Tehran will have to give more than it’s getting (especially in stopping progress on its heavy water reactor at Arak, as Fabius rightly insisted). If Tehran can’t make these concessions, the world will see that President Hassan Rouhani either can’t or won’t deliver the deal that will lift sanctions and give Iran a voice in regional security issues, such as Syria.

Given the seeming benefits of the deal, it’s curious that Netanyahu has set himself so adamantly against it. Netanyahu’s rejectionist stance directly challenges the authority of President Obama, who has invested the credibility of his administration in gaining this diplomatic resolution. It’s as if West Germany had denounced John F. Kennedy while he was in the midst of negotiating a deal to resolve the Cuban missile crisis in 1962.

Netanyahu seems to think that if sanctions have brought Iran to the table and gained concessions, then more sanctions will force Tehran to give up its nuclear program altogether. But administration officials fear that imposing more sanctions at this delicate moment (as Netanyahu is pushing the U.S. Congress to do) will just blow up the negotiations. The administration thinks that Tehran, rather than surrendering, may accelerate the nuclear program — producing the very result that Israel fears.

If Netanyahu’s capitulation demand doesn’t work, the next step presumably would be even more crushing sanctions, or eventual Israeli military action.

Here we return to the question posed by my Lebanese friends around the dinner table — about who will fill the power vacuum in the region. My sense is that Israel and Saudi Arabia would love to scuttle an American rapprochement with an Iran they regard as a deadly adversary. But if Obama presses ahead, Netanyahu is bidding to replace the U.S. as military protector of the status quo, including the security of the Gulf Arabs.

Strategically, this de-facto Israeli alliance with the Saudis is an extraordinary opportunity for Israel. And for Fabius, there’s a chance to position the French as the West’s prime weapons supplier to the Saudis, gaining France hundreds of billions of dollars in the post-American era in the Gulf. For opportunistic reasons, no wonder Israel and France want to detonate the U.S.-Iranian rapprochement. But will this really aid their security?

The Obama administration would counter (correctly, I think) that embracing the Saudi strategy of an ever-deepening Sunni-Shiite divide is unwise. The schism will fuel permanent sectarian war in Iraq, Syria and Lebanon. The Saudis now are blocking formation of any government in Lebanon, for example, to obstruct Iran’s ally, Hezbollah. In Syria, the Saudis seem ready to fight the Sunni-Shiite battle down to the last Syrian.

Better to seek a turn in relations with Iran through diplomacy that can limit its nuclear program, Obama reasons. He’s right.