I think it more like than not that there will be one because both sides strongly want it. I suspect that what we are seeing now just as all past times is that all sides are trying to get a bit more.
Remember that the framework actually surprised critics by being better and more complete then expected. The combination of Kerry and Moniz is powerful because of their mutual respect and friendship and the different skills they bring to the table.
I think they will team up to get the votes needed - even if it is just to prevent overturning Obama's veto. One strong argument might be that a vote against the deal is very possibly a vote for a path leading to war with Iran. In fact, where the Iraq war was likely to happen no matter what resolution passed, this really is a vote against a diplomatic solution.
Netanyahu has made it clear he will fight to get Congress to stop a deal. I hope our legislators take a good look and listen to the nonsense and lies that have come out of his mouth.