Before sitting down to negotiate with someone, make sure they have the authority to deliver their side of the deal. It is one of the cardinal rules for negotiating successfully.

For one side to be confident enough to make concessions, it must know the reciprocal concessions offered by the other will be honoured and additional demands will not be made at the last minute altering the delicate balance of compromise.

In the run-up to the last round of nuclear negotiations in Geneva, there was much speculation about whether Iran's Foreign Minister Mohammad Javad Zarif and President Hassan Rouhani had the necessary authority to reach an interim deal, or whether it would have to be referred back to Supreme Leader Ali Khamenei and then blocked if they made too many concessions.

In the event, it was US President Barack Obama and Secretary of State John Kerry who lacked authority to close a deal in the face of intense opposition from Israel, France and many members of the US Congress.

UNRAVELLING

Before the talks, US diplomats had spent months working in secret on confidence-building overtures with members of the Iranian government and the Supreme Leader's circle that were intended to signal US seriousness about doing a deal. The full extent of the groundwork was chronicled in a fascinating article in the Wall Street Journal ("US-Iran thaw grew from years of behind-the-scenes talks", Nov. 7).

By blocking the interim agreement that had been emerging, however, France has created serious doubts about the Obama administration's ability to close a deal and created more time for critics to rally congressional opposition, jeopardising the entire negotiating process.

It has also risked damaging the credibility of Iran's negotiators, led by Zarif and Rouhani, exposing them to domestic criticism from hardliners that they are making too many concessions without securing enough in return.

If the Obama administration wants to do a deal, it will have to face down opposition from foes including French President Francois Hollande, Israeli Prime Minister Benjamin Netanyahu and Congress to show it is in charge of US foreign policy and has the ability to deliver.

For the time being, the administration's ability to control policy towards Iran remains in question.

FULL POWERS

The US is probably the most difficult country on Earth to negotiate with because of the separation of powers, which gives both the president and Congress significant roles in foreign policy.

Foreign negotiators have often made concessions in negotiations with the president's diplomats only to find that Congress demands yet more concessions after a deal is supposed to have been reached.

Negotiating twice puts foreign countries at a severe disadvantage. In some instances it has enabled the US to secure a better deal for itself. But in others it has resulted in no deal at all, either because an agreement unravelled in Congress or because foreign governments would not risk signing a deal that could be picked apart subsequently by US legislators.

In this instance, Iran must negotiate not only with the US president but with Congress and Israel hovering in the background.

Diplomats have developed several mechanisms to overcome the double-negotiation problem. In trade talks, other countries have typically required the US president to obtain "fast-track" negotiating authority from Congress before signing a deal, enabling the president to put the deal to lawmakers for a straight up or down vote. Legislators can approve or block the deal but cannot amend it.

Other mechanisms for resolving the double-negotiation problem involve packaging a deal as a "single undertaking," in which all its elements are indivisible, and adopting the principle that "nothing is agreed until everything is agreed".

The US is not the only tricky interlocutor. Other countries have tried to obtain a negotiating advantage by reopening a deal after it was concluded or threatening to do so to secure extra last-minute concessions.

To overcome the problem, most diplomatic conferences open with a credentials committee, at which all diplomats must show that they have "full powers" to conclude a deal that binds their nations.

There is no question that Obama has the formal power to strike a deal, but there are considerable doubts about whether he has the informal authority to make it stick.

CLOSING A DEAL

The P5+1 negotiating process was meant to ensure the Western Allies and other members of the UN Security Council spoke with a single voice when dealing with Iran.

In effect, the US offered other members of the Security Council, notably Russia and China, participation in the talks process, under its own informal leadership, in exchange for their support in making sanctions effective.

Russia and China agreed to support the sanctions-plus-negotiations process in the hope it would avert a military attack on Iran's nuclear facilities.

Britain, France and Germany also appear to have backed the P5+1 process in the hope it would avoid military confrontation.

But the intense opposition from Israel and some members of the US Congress to the emerging deal and France's decision to demand extra concessions at the last minute risk undermining the entire P5+1 process.

The P5+1 is no longer speaking with a single voice. Diplomats have moved quickly to scotch talk about a rift, but the vehemence of the denials cannot conceal the reality that the P5+1 is now divided.

The P5+1 is clearly no longer under US leadership, or at least not the leadership of the president of the United States.

And given the mounting opposition Obama is facing at home and abroad, it is not clear the US president and by extension the P5+1 can close any deal that would be acceptable to Iran.

TALKS IN JEOPARDY

Following the breakdown of the last round of talks in Geneva, both sides have been careful to strike an optimistic note in public.

To keep the momentum going, there have also been further confidence-building measures. Britain and Iran have agreed to exchange charge d'affaires.

But the positive talk cannot disguise that the P5+1 process has sustained serious damage.

Iran has been left wondering with whom it is negotiating precisely: the president of the United States or its implacable foes in Israel and Congress.

Russia and China must be wondering about the deal, under which they have backed tough sanctions in exchange for a negotiating process that may not work.

But the most serious problems confront Obama and Hollande.

France's hardline position surprised many observers. It is still not clear whether France intended to block the emerging agreement or blundered by demanding last-minute concessions, which proved too far for the Iranian side, and was then caught out when the process collapsed.

Like the other Western Powers, France backed Saddam Hussein's Iraq during the war with Iran. But French oil company Total has substantial interests in Iran's oil and gas industry, which it hopes to revive once sanctions are lifted, all of which are now at risk.

For Obama, the bigger problem is not negotiating with the Iranians but with his own side and making sure they accept his leadership. US diplomats have slowed the pace of negotiations as they try to rebuild support on their own side.

Before Obama can strike a deal, he must be sure it will be accepted, or at least tolerated, at home by Congress and in the Middle East by America's allies, led by Israel and Saudi Arabia.

The US president must convince them the deal is the best that can be obtained or face them down and demonstrate his control of US foreign policy. - Reuters