Washington: 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.
The White House sought to temper optimism about a seemingly imminent nuclear deal with Iran today, 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.
"From our vantage point it is difficult to predict," said Earnest. "That is an 'X factor'."
Advertisement
"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."
Advertisement
COMMENTS
Advertisement
Joe Biden To Serve Full Second Term If Re-Elected: White House What White House Said On Parkinson's Doctor Visiting 8 Times In 8 Months "Run Against Me": Defiant Biden Digs In, Challenges Critics Within Party Massive Worldwide Microsoft Outage: Flights, Markets, Stock Exchange Down CrowdStrike Falcon Sensor: The Culprit Behind World's Biggest IT Outage "Fix Deployed": CEO Of Firm Behind Global Microsoft Outage Microsoft Outage "Affecting IT Operations" Paris Olympics Organisers In Jaw-Dropping Video, 12-Foot King Cobra Rescued And Released In Karnataka Biden Or Trump, It's Still A Long Wait For Indian 'Dreamers' In US Track Latest News Live on NDTV.com and get news updates from India and around the world.