Geneva, Switzerland (CNN) -- Amid increasing optimism that a deal could be within reach, U.S. Secretary of State John Kerry is heading to Geneva to help in negotiations over Iran's nuclear program. Kerry will fly to Geneva on Friday "in an effort to help narrow differences in negotiations" with Iran, two senior State Department officials said. European Union High Representative Catherine Ashton invited Kerry to the talks, the officials said. News of Kerry's travel plans came hours after Iran's foreign minister said that officials could reach an agreement by Friday evening. "I believe it is possible to reach an understanding or an agreement before we close these negotiations (Friday) evening," Iran's foreign minister and chief nuclear negotiator, Javad Zarif, told CNN's Christiane Amanpour.
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Obama: There is the "possibility of a phased agreement"
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Two senior State Department officials say Kerry will go to Geneva
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"It is possible to reach an understanding" before Friday night, Javad Zarif says
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European Union spokesman: Uranium enrichment is the focus of talks with Iran
The details were hashed out during a bilateral U.S.-@placeholder meeting -- part of an apparent effort on each side to mend fences -- which lasted about an hour on the sidelines of broader talks under way in Geneva.