Where is he? Immediately after 9/11, the mystery over Dick Cheney's whereabouts was an innocent source of mirth, that could even be justified by raison d'état. In those fraught times, it made a sort of sense that the man who would take over if George Bush fell under a bus should stick to his "secure undisclosed location" - even though many of us suspected that the location in question was one or another decent steakhouse in the Washington DC area.
These days, however, the joke has worn about as thin as the Bush approval ratings. Arguably the most influential Vice-President in American history has vanished into thin air. True, there are claims of the odd sighting: at a closed-door lunch of Republican Senators on Capitol Hill the other day, and at some private party fundraisers in the plusher suburbs of mid-western cities. But as President Bush's problems mount, Mr Cheney is nowhere in evidence. And into the vacuum left behind rumours pour.
The latest is that the two have fallen out. Up to a point the theory makes sense. Mr Cheney was the loudest advocate of the Iraq war; he bought the wildest WMD theories, he boasted how US troops would be festooned with garlands as they entered Baghdad, and argued (and continues to argue) that in the treatment of terror suspects, no holds should be barred. As Iraq slowly overwhelms his presidency, Mr Bush wouldn't be human if he didn't privately give vent to his feelings: "Dick, how on earth did you get us into this?" Then there's the CIA leak investigation. It is the top aide to Mr Cheney, not Mr Bush, who has been indicted, blowing away the myth that this administration is cleaner than its predecessor. The signs are that the President's men are belatedly tightening the reins on Mr Cheney's powerful national security staff, long an independent fiefdom. Again one can hear the frustrated President: "Dick, what have your guys been doing?" But we should not get carried away. Lewis "Scooter" Libby may have gone. But David Addington, Mr Cheney's new chief of staff, is no softie. He has long argued for unfettered presidential power and takes a dim view of such niceties as the Geneva Conventions and legal representation for captured terrorist suspects. Mr Cheney, in short, is not about to change his ways.
And whatever his discomfort, Mr Bush is joined to his Vice-President at the hip.
As recently as 18 months ago, a parting of the ways wouldn't have raised too many eyebrows. Mr Cheney could have used his dodgy heart as an excuse to step down, rather than undergo a gruelling re-election campaign. But it's too late now. Nothing would delight some Republicans more than for him to to step aside in favour of, say, the Secretary of State, Condoleezza Rice. But that would be seen, correctly, as an admission of error by Mr Bush. This President is no more inclined to admit mistakes than he is to dismiss old friends.
However, one basic fact is indisputable. Right now, Mr Cheney is the President's biggest single liability. With his Inspector Plod demeanour and that slow, lop-sided manner of speaking, Mr Cheney was never a barrel of laughs, even in his more benign days. Back before 9/11 this was acceptable enough. He was the safe pair of hands, the wise old curmudgeon; if anything it was reassuring to think that he and old partner Rummy, rather than a green and callow President, were running the country.
No longer. To be sure, Mr Cheney remains a useful bridge to the conservative wing of the party, even though America shows every sign of having had enough of the conservatives, especially in matters of foreign policy. But his grim, unsmiling features have become the symbol of an America that has lost the sunny optimism for which we once forgave it all its faults. Mr Cheney plays to the dark forces of suspicion and fear. His is a Hobbesian universe, in which the US must strike before it is struck.
This is the mindset that has led to the calamity of Iraq. Yet typically he refuses to budge. The other day, the Republican-controlled Senate voted 90-9 in favour of an amendment barring the use of torture by US forces. And Mr Cheney's reaction? He urged an exemption for the CIA, ignoring the pleas of party grandees such as John McCain that "this is killing us around the world", and newspaper headlines lamenting "The United States of Torture". Mr Bush still seems to buy this line. "We do not torture," he insisted after his wretched visit to Latin America - only to add that in the war against terrorists "anything we do in this effort, any activity we conduct, is within the law". The language was vintage Cheney. The invisible man will retain his power. Only when he is publicly sighted, attending the funerals of foreign dignitaries, chairing pointless commissions, doing what Vice-Presidents once were supposed to do, will we know the spell has been broken.