LAUSANNE, Switzerland — In a demonstration of what one US diplomat called “roller coaster” negotiations, there were signs March 17 that six world powers and Iran may need until the end of March to conclude a political agreement on major elements of a final Iran nuclear accord, after some hopes were raised March 16 that a deal might be possibly concluded by the weekend, when, among other things, the Persian New Year holiday begins.

Iranian officials said gaps on technical issues had narrowed to one major issue — thought to involve the scope of research and development that Iran could conduct under a final nuclear deal. However, a senior US official said March 17 that while technical talks between top Iran and US nuclear experts had been very productive, there was still a long way to go.

"The (technical) discussions … have been very, very professional and I think fruitful in terms of identifying the technical issues, clarifying and looking what our options are on the table for a potential agreement,” a senior US administration official at the talks, speaking not for attribution, told journalists here March 17.

"I am not going to get into specifics but we have definitely made progress in terms of identifying technical options for each major area,” the US official said. “And there is no way around it, we still have a ways to go."