The silver lining for fans of Article I of the U.S. Constitution is that with or without Corker-Cardin, and no matter what executive agreements are made with Iran, Congress retains the final say on when Congress-passed sanctions are permanently lifted (though it has no say on United Nations and European Union sanctions, which are also part of the international deal). Obama can only waive sanctions so long as he is around. The Iranians didn’t need Sen. Cotton’s letter to know that Obama can’t control what happens in 2017 and beyond.
Why isn’t that sufficient to soothe the hawks? Because while the next president and the next Congress could negate the deal, everyone knows they won’t if, after 18 months, Iran is in compliance and the rest of the world remains on board. As the Iranian foreign minister intimated last week, for the U.S. government to arbitrarily and unilaterally withdraw would be an incredibly belligerent and destabilizing act that would risk, if not deliberately instigate, all-out war.

That’s why the hawks want to short-circuit the deal now, before it gets off the ground. But they can’t without Democratic help, and even those Democrats who have expressed reticence about the emerging deal have (as predicted here) proved unwilling to undermine the president.

In sum, conservatives cannot get what they want through the legislative process, nor can they by thwarting the legislative process. That leaves them two choices as Corker-Cardin moves through Congress. They could raise hell in hopes it will move public opinion, despite polls consistently showing support for the deal. Or, they could calmly accept the political and legal reality – a reality of their own making –and move on to other issues.