If the Iranians can keep getting concessions from Kerry and Obama and they can drag this mess out long enough, they will have had time to build the dang bomb that this whole thing was supposed to prevent to begin with. The Iranians are playing Kerry and Obama for the fools that they are.
Kerry and Obama want an agreement, any agreement, even if it says that the Iranians get everything they want and US gives up everything we wanted. These two guys aren't negotiators. They are politicians who want a feather in their caps, even if the feathers are from a crow.