After two weeks of marathon negotiations, as well as a number of delays, a nuclear deal between Iran and the P5+1 world powers looks to be "within reach" on Sunday, a senior Iranian official announced.
"The deal is within reach today. But some issues remain that need to be resolved by foreign ministers," the official told Reuters.
US Secretary of State John Kerry also expressed optimism in Vienna on Sunday, albeit a bit more cautiously.
"I think we're getting to some real decisions," Kerry told reporters in the Austrian capital. "So I will say, because we have a few tough things to do, I remain hopeful. Hopeful."
The talks on a permanent deal between Iran and six world powers, which have already been extended several times and were to end Friday, were extended yet again through the weekend until Monday.
Major disagreements have so far included Iran's refusal to allow inspections on sensitive nuclear sites, its refusal to disclose the military aspects of its nuclear program, and in a newly added demand, Iran has called to end the UN arms embargo on it.
In a briefing with Israel over the weekend, US diplomatic officials noted that while significant gaps exist, there is still a great willingness, especially on the part of the West, to reach a compromise by Monday.
That optimism, however, is something of a departure from US President Barack Obama's recent assertion that the chances of a nuclear agreement with Iran are “less than 50-50."
Prime Minister Binyamin Netanyahu, meanwhile, blasted the West on Sunday for its latest string of concessions during the negotiations.