You can argue that this deal should have been different, but when it comes time to vote on whether it should go forward, members of Congress will be choosing between two options, neither of them hypothetical. A yes vote means all the parties — not only Iran and the United States, but also the United Nations, China, Russia, and the European Union — implement this deal. A no vote, in contrast, doesn’t mean that some fantasy deal will fall from the sky. It means that the U.S. walks away from this deal, and it collapses.
That also could mean that the existing sanctions regime collapses. We can keep our sanctions on Iran, but the reason sanctions have been so devastating to the country’s economy is that they haven’t just come from the U.S., but also from the United Nations, the European Union, and elsewhere. If those other sanctions were to disappear, Iran would get most of what it wanted without having to fulfill any obligations at all. And if they want to pursue a nuclear weapon, they could then go right ahead.
So now that the deal is on the table and congressional votes are on their way, what Republicans really need to explain is not what sort of deal they might have preferred. We know their answer to that question — they’ll say they would have rather had a deal where Iran gives us everything we want, and we give up nothing. But that’s irrelevant at this point. What they need to explain now is why the U.S. pulling out of this deal — and what happens afterward — will be preferable to implementing it, imperfections and all. Do they think the Iranians will come crawling back and make further concessions? Do they think the rest of the world’s powers, which support the deal they helped negotiate, will just follow us and impose new sanctions in the hope that eventually that might lead to more negotiations (which, like these, would take years) and ultimately the fantasy deal where Iran capitulates? What precisely is the chain of events Republicans think will occur if we pull out?