With talks at an impasse and a deadline one day away, Iran and six world powers on Sunday began discussing how to again extend their negotiations over Tehran's disputed nuclear program.
Secretary of State John F. Kerry, Iranian Foreign Minister Mohammad Javad Zarif and top diplomats from France, Britain, Germany, Russia and China met for a sixth day of frantic meetings in the Austrian capital seeking a deal aimed at ensuring that Iran's nuclear program remains peaceful.
But while they insisted that they were still working toward reaching a final deal before Monday's deadline, they acknowledged for the first time that the discussion includes how to continue the talks for a few more months to try to pin down what they hope will be a historic pact.
The group has been trying since February to negotiate a deal that would ease tough international sanctions on Iran's economy if Tehran agrees to restrictions aimed at preventing it from acquiring the capability to make nuclear weapons.
The parties had sought to keep the focus on getting a final deal, hoping that, as in many negotiations, the approach of a deadline might lead to important last-minute concessions.
But after days of intense meetings in which the same ground was covered, diplomats acknowledged that they have no choice but to seek a way to find additional time for more discussions. Diplomats insisted that the talks, which come in the 11th year of diplomacy over the disputed program, are not near a breakdown.
But another delay, following a four-month extension announced in July, will open the Obama administration and the Iranian government to domestic criticism from conservatives who fear their side will make dangerous concessions.
Officials played down speculation that current talks would conclude with a "framework" agreement that would spell out in broad terms how they intend to settle the small number of major issues that remain unresolved. It appears more likely that the two sides will continue their talks under terms that are similar to those contained in an interim nuclear agreement signed on Nov. 24, 2013.
Iranian officials said the new extension was likely to last at least four months, but perhaps as long as a year. But some Western officials said the issue remained unresolved.
A deal could ease a top security threat and open the way to a better U.S.-Iran relationship.
President Obama, in an interview with ABC News' "This Week," seemed to signal that he thought a deal unlikely, saying that "the gaps are still significant." But he argued that the negotiations of the last year have been beneficial because they have been based on an interim nuclear deal that has temporarily halted some of the most worrisome parts of the Iranian nuclear program.
Obama ruled out the idea that the six countries would quickly and irreversibly lift sanctions on Iran.
"We can't do that," he said, suggesting that sanctions would be only temporarily suspended until Iran proved it would abide by its commitments under the deal.
Obama said an agreement would lead to significant changes.
"What a deal would do," he said, "is take a big piece of business off the table and perhaps begin a long process in which the relationship not just between Iran and the U.S. but the relationship between Iran and the world, and the region, begins to change."
That promise may appeal to many Iranians. But it could alarm U.S. allies in the Persian Gulf and Israel, who fear that the United States might align itself with their regional rival.
Extending the talks without negotiating a new interim agreement is the quickest and easiest way to continue talks, because any new terms could be contentious.
The two sides have made progress on many issues, but still disagree on the difficult core issues of how much uranium enrichment capacity Iran could maintain, and the pace at which the international sanctions would be removed.
Kerry met twice Sunday with Zarif and held a session with Russian Foreign Minister Sergei Lavrov. He dined with the foreign ministers of Britain, France and Germany, and spent one hour at the Vienna airport meeting in the plane of Saudi Foreign Minister Saud al Faisal to discuss the nuclear issue.
The six countries are expected to hold a joint session Monday and presumably many smaller gatherings as well.
Meanwhile, in Iran, where conservatives and reformists have been sharply divided over the benefits of a deal, there are signs that some conservatives are now supporting an agreement because Iranian negotiators have laid down a tough set of demands.
For example, provincial prayer leaders in Iran were unanimous Friday in expressing support for Zarif's team in Vienna. The imams are appointed by Iran's supreme leader, Ayatollah Ali Khamenei, and their views reflect his.
Etemad, a reformist newspaper, described this backing as "unprecedented."
The leaders of the Iranian Revolutionary Guard Corps, the hard-line Javan newspaper and the army have also offered words of support for the negotiating team in recent days. Some conservatives, however, rallied Sunday in opposition to any agreement.
Mark Fitzpatrick, a nonproliferation specialist with the International Institute for Strategic Studies in London, said support from conservatives indicates that "the various factions in Iran have come together in a general consensus about what they have to have from the negotiations. The bar they have set appears to be too high to enable a deal."
Yet, he added, this broad support "may give Zarif some latitude for maneuver."
Israeli Prime Minister Benjamin Netanyahu, after a phone call with Kerry, said he understood that the deal would enable Iran to keep thousands of centrifuges, and urged the six world powers not to sign a bad agreement.
"There is no reason why it should be left with thousands of centrifuges that could enable it to enrich uranium for a nuclear bomb in a short time," Netanyahu said before his weekly meeting with his Cabinet.
Netanyahu said he would prefer to see world powers continue the current sanctions to a deal he believes would be dangerously lenient.
Special correspondent Ramin Mostaghim in Tehran and Times staff writer Laura King in Jerusalem contributed to this report.