Obama will be remembered ultimately for the Iran treaty, as Johnson is remembered for Vietnam. Like Johnson, Obama is wrapped in a warm blanket of advisers who flatter his earnest, high-school views of world politics. Like Johnson, he lives in his own delusional world in which he’s commander-in-chief not merely of the military but of the whole blessed nation. Like Johnson, he has been destroyed by the arrogance of power; and his blindness has endangered America. Unlike Johnson, he was never big enough for the job in the first place.

Iran’s Supreme Leader reeks of blood. Obama’s treaty reeks of disgrace and surrender. Vietnam did disastrous damage to America’s military, its intelligence services, and its international standing — damage compounded by Richard Nixon’s crookery and Jimmy Carter’s entire presidency. It took Ronald Reagan to repair the wreckage. Will there be a Reagan to clean up after Obama? — to the extent the damage is reparable? Reagan was the man he was because he was unbudging at the core, and because his sunniness and cheerful decency lifted the nation’s spirits. Have we got a candidate today with an unbudgeable core and a winning, sunny, gigantic personality? Those are the criteria that matter at this sobering low point in modern American history.