Those whom the gods will destroy they first make mad. Critics of Barack Obama’s Iran deal have been giving a good impression of having lost the plot. An Israeli cabinet minister described it as “one of the darkest days in world history”. Republicans liken Mr Obama to Neville Chamberlain. All agree that a deal that removes about two-thirds of Iran’s nuclear capability and freezes the rest will somehow hasten the day it has the bomb. In the next two months, before Capitol Hill votes on it, we will hear a lot more such bombast. It comes down to whether Congress believes Iran is capable of acting rationally or whether it is a uniquely malevolent country that has outfoxed America and its partners in the negotiating chamber.

The chances are that Mr Obama’s deal will prevail. He needs the veto-proof support of just a third of each chamber — 34 senators and 145 in the House of Representatives. Even then, however, it is no sure bet. In the next 60 days it will face the onslaught of Israel, Saudi Arabia, and every Republican presidential hopeful. In addition to viewing Iran in an apocalyptic light, each has further motives for wishing to sink the deal.

In the case of Saudi Arabia, the logic is simple. Iran is Saudi Arabia’s chief competitor that claims to speak for the region’s Shia minority, a large chunk of which lives in Saudi Arabia’s oil-rich east. In a sectarian zero-sum game, anything that boosts Iran is bad.