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Negotiations over Iran's nuclear programme entered their 17th - and possibly last - day in Vienna today as diplomats continued to haggle over details ahead of the expiration of an interim accord.
With the temporary deal set to expire at midnight tonight Vienna time, diplomats said they were planning to complete and announce a final agreement before day's end.
But, they warned there was no guarantee with several issues still unresolved. The deadline for the end of the current round of negotiations has already been extended three times and the diplomats said there was little appetite for a fourth.
Iran's deputy foreign minister, Abbas Aragchi, told reporters in Vienna that the talks are at their "final breathtaking moments (but) certain issues still remain."
In Brussels, French President Francois Hollande said the sides are near agreement but "a gap" remains.
The foreign ministers of Russia and China, who had left the talks last week, both returned to the Austrian capital late yesterday, and most other foreign ministers of the seven nations at the table also were in Vienna today, in place for any announcement.
"The foreign ministers are gathered to bring negotiations to a conclusion," said Chinese Foreign Minister Wang Yi. "We believe there could not be further delay."
After more than two weeks of see-saw developments, including threats from both the United States and Iran to walk away, senior officials at the talks began expressing optimism that a deal was in reach yesterday.
US Secretary of State John Kerry said twice that he was "hopeful" and met again with Iran's Foreign Minister Mohammad Javad Zarif last evening.
After that meeting, foreign ministers and senior officials from the five permanent members of the UN Security Council and Germany held a group dinner.
French Foreign Minister Laurent Fabius told reporters yesterday that he believed the negotiations were entering their "last phase."
In Iran, President Hassan Rouhani said an agreement was close, but not quite done, describing the negotiations as "still steps away from reaching the intended peak."
Movement toward a deal has been marked by nearly a decade of wearying negotiations. The pact is meant to impose long-term, verifiable limits on nuclear programs that Tehran could modify to produce weapons.
Iran, in return, would get tens of billions of dollars in sanctions relief.
