DONE DEAL:

"In terms of completing the comprehensive deal by Nov. 24, I would say the probability is very near zero," Robert Einhorn, a nuclear expert who previously served on the US-Iran nuclear negotiating team, told an Arms Control Association conference on Oct. 20.

But Einhorn said he thought one option would be that there could be agreement reached on a "cluster" of key issues (such as enrichment capacity, modifications to the unfinished Arak research reactor, etc.) reached by the Nov. 24 deadline that would justify a few more months to finalize the remaining technical details.

If the parties "reached agreement on a cluster of these issues, they would have a strong case to justify taking several more months," Einhorn said. "That may or may not be possible."

Other experts said US officials had suggested that they believe they genuinely have a shot at getting the whole thing done by Nov. 24.

"They are definitely in a new phase," one expert, speaking not for attribution, told Al-Monitor, referring to the US negotiating team. "The new phase is preparing the ground for the deal."

"Can they get a comprehensive agreement with the technical appendices" by the deadline? the expert said. "Yes, they can."

Follow @brothersjudd