Nuclear program of Iran
U.S. President Obama reportedly sent a letter dated 20 April 2010 to President Lula of Brazil, in which he outlined a proposal of fuel swap. While expressing skepticism that the Iranians would now be willing to accept such a deal, having provided "no credible explanation" for the previous deal's rejection, President Obama wrote "For us, Iran’s agreement to transfer 1,200 kg of Iran’s low enriched uranium (LEU) out of the country would build confidence and reduce regional tensions by substantially reducing Iran’s LEU stockpile." Turkish Prime Minister Recep Tayyip Erdogan received a similar letter. A senior U.S. official told the "Washington Post" that the letter was a response to Iran's desire to ship out its uranium piecemeal, rather than in a single batch, and that during "multiple conversations" U.S. officials made clear that Iran should also cease 20% enrichment; however, the official stated "there was no president-to-president letter laying out those broader concerns".
Government of the Islamic Republic of Iran
The current President of Iran is  Hassan Rouhani, who assumed office on August 3, 2013, after the 2013 Iranian presidential election. He succeeded Mahmoud Ahmadinejad, who served 8 years in office from 2005 to 2013.