For the Saudis and the other Gulf Arabs, this is a nightmare. They’re engaged in a titanic regional struggle with Iran. And they are losing — losing Yemen, losing Lebanon, losing Syria, and watching post-U.S.-withdrawal Iraq come under increasing Iranian domination.

The nightmare would be hugely compounded by Iran going nuclear. The Saudis were already stupefied that the U.S. conducted secret negotiations with Tehran behind their backs. And they can see where the current talks are headed — legitimizing Iran as a threshold nuclear state.

Which makes all the more incomprehensible President Obama’s fierce opposition to Congress’s offer to strengthen the American negotiating hand by passing sanctions to be triggered if Iran fails to agree to give up its nuclear program. After all, that was the understanding Obama gave Congress when he began these last-ditch negotiations in the first place.