A group of 47 Republicans, including Senate leaders and several potential 2016 presidential candidates, has written an open letter to Iran's leadership warning that any nuclear deal it signs with the current administration won't last after President Barack Obama leaves office. Obama is in office until January 2017. His successor could scrap any agreement if the US Congress has not approved it. “I think it's somewhat ironic to see some members for Congress wanting to make common cause with the hard-liners in Iran. It's an unusual coalition,” Obama said on Monday, 9 March, ahead of a meeting with European Council President Donald Tusk. While the Republican members of Congress hope to discourage Iranians from continuing negotiations with Western powers, they may have to come up with another plan, since their trick hasn't worked. Early Tuesday morning, Iranian Foreign Minister Mohamed Javad Zarif went on social media and fired back to Senator Tom Cotton, the author of the letter to the government of Iran. Zarif dismissed as of “no legal value” the US senator's letter. He expressed astonishment that “some members of US Congress find it appropriate to write to leaders of another country against their own president and administration.” He added, “Any congressional action to prevent the implementation of any agreement will violate the international commitments of the [US] government.” The letter marked a rare foray by Congress into US foreign policymaking, as negotiations with foreign governments are a responsibility typically handled by the executive branch, not lawmakers. “From reading the open letter, it seems that the authors not only do not understand international law, but are not fully cognizant of the nuances of their own constitution when it comes to presidential powers in the conduct of foreign policy,” Zarif said in response to Cotton on his Twitter account. While the verbal war continues, Iranian and US negotiators appear even more determined to tackle the nuclear issue before time runs out. The nuclear talks, round 13 in a series, are due to resume 15 March in Lausanne. Negotiators are preparing for high-level ministerial meetings of the P5+1 (the five permanent members of the UN Security Council plus Germany). The talks are scheduled to take place between 15 and 20 March. It remains unclear whether or not the agreement's framework will propose a comprehensive deal. The details of the talks are highly secret. After the last meeting, in Montreux, Switzerland, last week, US Secretary of State John Kerry headed to Saudi Arabia to brief the new Saudi king and also the foreign ministers of Iran's regional neighbours, who had gathered in Riyadh. From Riyadh, Kerry went to Paris to meet his French and British counterparts to exchange thoughts on the latest developments in the talks. Kerry's intense shuttle diplomacy and consultations with key US allies gave observers the impression that a nuclear deal is close to hand. Western nations long suspected that Iran is covertly pursuing nuclear weapons capability. However, Iran shows signs that it wants to secure a deal. In an interview with the Tehran-based Sada magazine, Zarif said a possible agreement between Iran and Western powers on the nuclear issue should become a Security Council resolution under Chapter VII of the UN Charter, and thus approved as an international agreement and binding on all states. This proposal ⎯ asking that any deal become a UN resolution ⎯ expresses Iran's uncertainty about the post-Obama period. A UN resolution would secure any agreement, no matter who is the next president of the United States. The deadline of 24 March is very important for President Obama to prove to the US Congress that there is progress in the talks and to prevent Congress members from imposing new sanctions on Iran, which could lead to a collapse of the talks. Both sides say that if they don't succeed in reaching an agreement by the 24 March deadline, the continuation of talks would no longer be necessary. Iran has been threatening to walk out of negotiations if new sanctions are imposed by the US Congress, while the US Congress wants to see that after a year and half of talks Iran's nuclear programme has been curbed and the country can't produce nuclear weapons. Ahead of the 15 March meeting in Lausanne, the International Atomic Energy Agency (IAEA) agreed to hold a technical meeting in Tehran on Monday, 9 March. The IAEA delegation will be headed by the organisation's deputy director general. The first interim agreement on the Iranian nuclear issue was reached on 23 November 2013 in Geneva, with an aim to reach a comprehensive deal within six months. Twice since, the interim agreement has been extended. It is now clear to the Iranians and Americans, as well as Western powers, that if no deal can be signed this time, no further extension would help. Little is known about the flexibility of Iran's supreme leader over these talks, or whether or not the details of a perhaps ready-to-sign agreement with Western powers may have already been presented to him and agreed upon. Many world leaders have expressed concern over a possible agreement with Tehran and asked negotiators to focus on Iran's regional and international behaviour, as well as addressing worries over its nuclear programme. Iran is asking for guarantees that sanctions will be lifted once an agreement is reached. But some observers say that Iran also needs to be ready for the post-sanctions period and to prove that it is a dependable business partner. A diplomat who sits on the UN Security Council told Al-Ahram Weekly off the record that all things could be achieved by continuing to increase transparency, as well as by avoiding aggressive policy actions in both the domestic and foreign spheres. Aggressive foreign policy stances create fear in the business community, no matter if the nuclear issue has been resolved, he said. “The nuclear talks are essentially a trust-building exercise. But the work is not over once a final deal is reached. A Comprehensive Joint Plan of Action (CJPOA) will just be the beginning of reassuring the world that Iran is a reliable and useful partner,” said the diplomat.