Iran's foreign minister Javad Zarif, walks after after talks with Secretary of State John Kerry in Lausanne, Switzerland, on March 17, 2015.

Iran's foreign minister Javad Zarif, walks after after talks with Secretary of State John Kerry in Lausanne, Switzerland, on March 17, 2015. Brian Snyder/AP

The 4 Things You Need for an Iran Deal

As negotiators meet this weekend, here are the political and technical challenges that lie ahead.

Like characters in a road-trip movie that has dragged on far too long, foreign ministers from seven nations slog back to Switzerland this week for what all hope will be the climax of the film. The talks have already been extended twice. No one wants a Hangover III.

The goal is to conclude a political framework for a deal that would roll back and constrain Iran’s nuclear program. U.S. officials say they can see a “path forward” to reaching the major elements of a deal by the end of March. Some believe it can be done by Sunday, March 29.

Experts from the seven countries (the United States, United Kingdom, France, China, Russia, Germany and Iran) would then have until a self-imposed deadline of June 30 to hammer out the technical details.

Hyperventilation about the deal has reached new extremes, as opponents flood the news media with new issues and new charges. But to conclude a deal in the next few days, the diplomats will have to solve four major challenges:

Preserve the unity of the P5+1. The six nations negotiating with Iran, known collectively as the P5+1 (for the five permanent members of the UN Security Council plus Germany), have been remarkably united over the 18 months of negotiations. French Foreign Minister Laurent Fabius, however, balked as the group neared agreement earlier this month, forcing a break in the talks. Some believe it was motivated by French pride or French contracts with Israel and Saudi Arabia and hoped-for contracts with Iran.

France, however, has traditionally been hawkish on Iran. Ten years ago, the French refused to go along with a compromise that would have allowed Iran to keep a few hundred centrifuges, insisting that with enrichment, “You cannot be a little bit pregnant.” That — and the refusal of the U.S. to join the talks then underway with France, Britain and Germany—caused the deal to collapse. It was followed by a decade of increasing sanctions and Iran’s increasing installation of centrifuges to today’s inventory of over 20,000. Resolving French concerns and keeping the group united will be a key to success.

Deal with Iranian politics. Iranian Foreign Minister Javad Zarif was roundly criticized at home after he took a walk with Secretary John Kerry during a break in the talks earlier this year. "Given the Great Satan's endless demands and sabotage during the course of the nuclear negotiations, there is no conceivable ground for intimacy between the foreign ministers of Iran and America," said a petition circulated by hardline opponents. The opposition, however, has been kept in check recently. This may signal Iranian willingness to make some final compromises that could seal the deal.

A bigger problem is that Supreme Leader Ali Khamenei says he doesn't want a written agreement at this stage, preferring to sign only one agreement in June. It will be close to impossible for the other nations to leave with just a handshake on what many believe could be the most important foreign policy agreement of the decade. The next few days will reveal whether the Supreme Leader is an unyielding opponent or a very crafty negotiator.

Deal with American politics. Although the talks with Iran remain broadly popular among the American public, with about 68 percent favoring them in a recent CNN poll, conservative critics continue to pound President Obama for what they see as appeasement.

Leaks from the talks—some the result of Israeli spying on the closed-door negotiations, according to the Wall Street Journal—continue to inflame Congressional opposition. With Congress in recess for two weeks, the U.S. team will have until mid-April to conclude a deal before Senators take to the floor with new sanctions and other bills.

If an agreement can be struck within the next few days, President Obama and diplomacy supporters may be able to consolidate public support for the deal before Congress can kill it. Major missteps by the opposition have helped, including the invitation to Israeli Prime Minister Benjamin Netanyahu to address Congress, the nearly universally panned letter by 47 Republican Senators to Iran’s Supreme Leader, and recent calls to begin a new war with Iran by architects of the Iraq War, most notably former Bush Administration official John Bolton.

Resolve the final two nuclear issues. Ironically, the final two challenges facing negotiators may be the easiest to resolve. One by one, the most difficult issues have been solved, or at least penciled into a possible final agreement.

If reports are accurate, Iran’s uranium enrichment capabilities will be slashed by some 70 percent, to around 6,000 centrifuges and Iran’s ability to make plutonium for a bomb will be practically eliminated. Most importantly, Iran will agree to unprecedented inspections that should allow for the rapid detection of any cheating and help uncover any secret facilities. International Atomic Energy Agency Director General Yukiya Amano told a gathering of nuclear experts this week that with the new inspection procedures, “If there is any abnormality, we can detect the change on the following day, on the very same day or in one week’s time.”

Former Iranian negotiator and State Department official Robert Einhorn said this week, this agreement “can effectively prevent Iran from acquiring nuclear weapons.”

Nothing is agreed to in the final deal until everything is agreed to. The remaining issues negotiators must resolve deal with limitation on research and development of new types of centrifuges and with the pace and sequencing of sanctions relief. Both are tricky and will require flexibility from all sides, but are relatively easier to solve than the problems already negotiated.

Secondary issues, such as those concerning the process for resolving questions related to Iran’s past nuclear program, also present a challenge. And it is unlikely that anyone will emerge from the talks with everything they wanted. But as Einhorn cautioned, “It’s very important for critics of the emerging deal not to engage in wishful thinking about prospects for getting a much better deal.”

If the talks should fail, the only real alternatives are watching Iran proceed with an unconstrained program that would rapidly bring it to the threshold of a nuclear bomb, or John Bolton’s new war with one of the largest military powers in the Middle East.

That is not a sequel that anyone will want to watch.