Washington: The White House sought to temper optimism about a seemingly imminent nuclear deal with Iran on Tuesday, warning that some difficult issues are yet to be resolved.
"In the mind of the president the odds have not moved," said White House spokesman Josh Earnest, warning that "at best" it is a 50/50 proposition.
The US administration reacted coolly to the confidence of Iran`s nuclear chief Ali Akbar Salehi, who was quoted as saying that "90 percent of the technical issues" had been agreed.
"The president is driving a very hard bargain and Iran is going to have to make some very tough and specific commitments," said Earnest.
The White House said that it remained to be seen if Iranian leaders, including those not directly involved in negotiations, would sign on to the agreement.
"From our vantage point it is difficult to predict," said Earnest. "That is an `X factor`."
Earnest said that there had been "substantial progress" over the course of the last year, but "as they encountered stumbling blocks they just delayed them to the end."
"Some of the most difficult issues, some of the issues that they have been struggling with for the longest period of time are the issues that have yet to be resolved."
The agreement would limit Tehran`s nuclear program for 10 to 15 years in return for sanctions relief.