It really doesn't matter who in congress is against it. And I couldn't care less what Saudi Arabia does.
All congress can do is vote to keep u.s. sanctions in place.
As for Israel, the billion and a half extra in aid will bring them some solace I'm sure....and defense contractors as well.
Here's this, regarding congress
http://www.cnn.com/2015/07/16/politi...ess-iran-deal/
Also, note, this isn't a tresaty between us and Iran, thus the voting is different. A simple majority vote to say yes or nay. If nay, Obama would veto...and then congress would have to get 2/3rds