Defenders of Barack Obama’s Iran deal ask a seemingly practical question of its critics: What would you do instead? But that question is only seemingly practical, not actually practical. The deal won’t go into effect only if two-thirds of both houses of Congress vote to override a presidential veto of a joint resolution of disapproval. Ten Democratic senators and 43 Democratic House members could defect from the president’s camp—and still the deal would become binding. There’s unrest among congressional Democrats over this agreement, but not that much unrest.