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A question fascinates Washington. Where's Hillary Clinton? Not physically, of course – for the Secretary of State, having given what was officially billed as a major foreign policy speech in the capital last week, is at the time of writing on a week-long visit to India and Thailand – but in the metaphorical sense that most obsesses this power-obsessed city: her place in the hierarchy of power by which its ruling caste is defined.

Not long ago, the former First Lady, the woman who would now surely be president but for the once-in-a-lifetime obstacle of Barack Obama, was supposed to be the other dazzling star of the new administration. And would not the Clinton name and the Clinton connections reverse the gradual decline of the State Department, long...