U.S. Secretary of State John Kerry has said the United States and other major powers are not in a rush to reach a nuclear deal with Iran.
He was speaking on July 9 in Vienna, where negotiators from Iran, Britain, China, France, Germany, Russia, and the United States are working to strike a comprehensive accord under which Tehran would curb its nuclear program in exchange for sanctions relief.
Kerry said, "We're here because we believe we are making real progress."
But he cautioned that he was prepared to "call an end" to talks with Tehran if "tough decisions" are not made.
EU foreign policy chief Federica Mogherini told CNN, "We are very close but if the important historical, political decisions are not made in the next hours, we won't [have] an agreement."
Meanwhile, Iranian Foreign Minister Mohammad Javad Zarif said he was prepared to stay at the negotiating table "as long as necessary" to clinch a deal.
"Hopefully today is the last day," added Iranian nuclear chief Ali Akbar Salehi as he headed into a meeting with U.S. Energy Secretary Ernest Moniz.
Moniz said they were "going to resolve the last issues, if we can.”
Russian Deputy Foreign Minister Sergei Ryabkov said he could not rule out that there would be an agreement “in the coming hours if the sides show the political will.”
But Iran's state media quoted an Iranian official as saying it was unlikely an accord would be reached on July 9.