At present due to oil hovering around $42 per barrel, this will have huge political consequences. First of all all the GOP candidates will oppose the Iran deal, because if they also can start putting more oil on the market because of the lifting of sanctions, the price may drop even further, Since the Koch brothers own most of the tar sands etc. as well all the oil industry will be hurting ( we started a war in Iraq because of wanting their oil) they will do everything to stop a deal with Iran. Also the new relations with Cuba sit not very well with the GOP, Marco Rubio protested and also mentioned no deal with Iran and even stronger sanctions.
So it is very clear who runs the show at the GOP; it is the oil industry as well the Koch brothers.