Negotiators make last-ditch effort to reach Iran nuclear deal March 29, 2015The US and Iranian teams during on of the negotiation sessions. (REUTERS/Brendan Smialowski)(REUTERS/Brendan Smialowski)Negotiators make last-ditch effort to reach Iran nuclear dealWith only two days left to the deadline, the P5+1 countries are making a vigorous effort to finalize a framework Iran nuclear deal. After 18 months of negotiations and only two days away from the March 31 deadline for a framework Iran nuclear deal, which would be finalized by the end of June, the US and Iran are expressing optimism, although it appears that no agreement has been finalized and that obstacles remain.Amid signs of trouble in the negotiations, US Secretary of State John Kerry cancelled plans Sunday to return to the United States for an event honoring his late colleague, Senator Edward Kennedy, in order to remain at the ongoing talks in Switzerland.Secretary of State Kerry during the negotiations. (REUTERS/Brendan Smialowski/Pool)The State Department said that Kerry had been looking forward to participating in the dedication of the Kennedy Institute in Boston with the family of the late Massachusetts senator on Sunday and Monday, but “given the ongoing nuclear negotiations in Lausanne, Switzerland, the secretary regrets he will not be able to share this special time with them in person.” Kerry served in the Senate with Kennedy for nearly 25 years and they were close friends.Kerry’s decision not to leave Switzerland comes as the talks appear to have hit obstacles ahead of the deadline on Tuesday. Officials have spoken of the hurdles in general terms, citing Iranian resistance to limits on research and development and demands for more speedy and broad relief from international sanctions.Read Iran planning unprecedented attack if Israel retaliates for ballistic missiles - reportNegotiators have already met multiple times in various formats and are continuing to do so around the clock. Kerry has been in discussions with Iranian Foreign Minister Mohammad Javad Zarif in Lausanne since Thursday.The foreign ministers of France and Germany arrived on Saturday, and those of Britain, China and Russia are due Sunday.The State Department said late Saturday that “serious but difficult work” remained for negotiators and that the pace of discussions expected to intensify as “we assess if an understanding is possible.”“In negotiations, both sides must show flexibility,” Zarif said on Twitter. “We have, and are ready to make a good deal for all. We await our counterparts’ readiness.”French Foreign Minister Laurent Fabius told reporters upon arrival in Lausanne that he hoped for “a robust agreement.”“Iran has the right to civil nuclear power, but with regard to the atomic bomb, it’s ‘no’,” he said. “We have moved forward on certain points, but on others not enough.”“The endgame of the long negotiations has begun,” German Foreign Minister Frank-Walter Steinmeier said. “And here, with a view of the Swiss mountains, I’m reminded that as one sees the cross on the summit, the final meters are the most difficult but also the decisive ones.”Iranian President Hassan Rouhani announced on Twitter that he had spoken with German Chancellor Angela Merkel, who agreed with him on the need for a resolution of the nuclear issue. Earlier this week, Rouhani sent a letter to the heads of state of all six global powers, including US President Barack Obama, with the same message. He also spoke on the phone with five of the six leaders – not with Obama.Read Israel strikes inside Iran, destroys 'vital components' of ballistic missile systemSeveral Iranian officials denied that Iran was close to agreeing on the document, but a Western diplomat said such comments were aimed at a domestic audience. “The difficulty is that the Iranians are not moving enough. They like to negotiate right up to the precipice and they’re very good at that,” he said.Will Obama Capitulate to Iranian Demands?Iran claims that its nuclear ambitions are purely peaceful while the West fears it is seeking to develop nuclear weapons. Yet progress has reportedly been made on the main issue: The future of Iran’s uranium enrichment program.Iran has the capacity to produce nuclear material for energy, science and medicine, but also for the fissile core of a nuclear weapon. The sides have tentatively agreed that Iran would run no more than 6,000 centrifuges at its main enrichment site for at least 10 years, while restrictions would gradually be eased over the next five years on that program and others that Tehran could use to make a bomb.Anti-aircraft guns guarding Natanz Nuclear Facility. (Wikipedia)The fate of a fortified underground bunker at Fordo previously used for uranium enrichment also appears closer to resolution, as the US may allow Iran to run hundreds of centrifuges at the bunker in exchange for limits on centrifuge work and research and development at other sites. The Iranians would not be allowed to do work that could lead to an atomic bomb and the site would be subject to international inspections. Any centrifuges permitted at Fordo would be fed elements used in medicine, industry or science instead of uranium.Read Biden-Harris admin promotes Pentagon employee tied to Iranian influence networkEven if the centrifuges were converted to enrich uranium, there would not be enough of them to produce the amount needed to make a weapon within a year — the minimum time frame that Washington and its negotiating partners demand.A nearly finished nuclear reactor would be re-engineered to produce much less plutonium than originally envisaged.Still problematic is Iran’s research and development program. Tehran would like fewer constraints on developing advanced centrifuges than the US is willing to grant.Also in dispute is the fate of economic penalties against Iran. In addition, questions persist about how Iran’s compliance with an agreement would be monitored. Staff (AP and Reuters contributed to this report.) FabiusIranKerrySteinmeierZarif