within the world soccer organizationhave brought "shame and humiliation" on the sport.Mr. Blatter spoke Thursday at the openingof the FIFA Congress in Zurich, Switzerland.He was speaking publicly for the first timesince U.S. and Swiss officials announcedmajor corruption investigations of the organization.Meanwhile, two major European football associationscalled on Mr. Blatter to resign,ahead of the organization's presidential elections planned for Friday.UK Prime Minister David Cameronalso supported calls for Sepp Blatter to step down.Major FIFA sponsors like Visa and Coca-Colaare calling for FIFA to make major changes within the organization.The United Nations is also reviewing its partnershipswith FIFA following allegations of widespread corruption,a U.N. spokesman said Thursday.Seven high-ranking currentand former FIFA officials were arrested Wednesday.Iranian Foreign Minister Mohammad Javad Zarif said Thursdayhe is hopeful Iran and a group of world powerscan reach a final agreement on his country's nuclear program"within a reasonable period of time."But during a visit to Greece, Zarif also saidan agreement will not happen if there are "excessive demands."Iran and the group that includes Britain, China, France, Russia,the United States and Germany have given themselvesuntil June 30 to form a final deal curbing Iran's nuclear activityin exchange for sanctions relief.The two sides agreed to a framework in April,but still need to work out details such as how quicklyto lift the sanctions that have hurt Iran's economy.Just a week after entering the Twitter worldwith his new handle, @POTUS,U.S. President Barack Obama was on Twitter Thursdayanswering questions on climate change.The president was in Miami, Florida, on Thursday,touring the National Hurricane Center.Mr. Obama spoke about the link between deadly storms and climate change.During his Twitter question-and-answer session Thursday,the president was asked by one userwhy he called climate change a national security issueduring his State of the Union address in January.@POTUS responded saying, more severe weather eventslead to displacement, scarcity, stressed populations;all increase likelihood of global conflict..