America - Andrew Stephen examines the box on Bush

George W Bush might not have been wired to a box in his back during the first televised debate, but

So what was that mysterious bulge under George W Bush's jacket? Is he on medication? Why did he blink repeatedly during the second presidential debate? Why did he postpone his annual medical check-up that was due last August? Is he suffering from pre-senile dementia?

These are all questions that have been put to me in the past few days. The evidence sounds convincing that Bush uses a "passive transducer earpiece", through which he is fed a script that has been transmitted to and then from a device hidden on his body; photographs from the first presidential debate on 30 September show what appears to be a box, placed underneath his jacket and between his shoulder blades.

There is more. The conspiracy theorists say that CNN has broadcast a film of Bush speaking, in which the soundtrack of somebody reciting his lines a second or so before he speaks is detectable. The pictures from the first debate have not been faked: the box outline is equally clear in video footage from the Fox News Channel feed. Bulletproof vests or back braces - other possibilities - do not fit the shape on Bush's back.

I have listened to the CNN tape, and what I heard sounded to me like Bush's own voice preceding his words in identical speech patterns; the broadcast did not go out live but was taped, so I concluded that there were audio problems which produced an echo on the soundtrack. And though replays of the Fox feed do show the same box shape at certain times, at others the box morphs under the television lighting, turning from the outline of a square to what appears to be a blurry rectangle.

My conclusion so far? The 43rd US president badly needs a new tailor, and Fox should get better lighting engineers. To the other questions, I can offer only opinions. I tend to believe, for example, that Bush probably takes medication to calm his nerves. I remember the contrast between when I saw him at the White House shortly after 7pm on 20 September 2001 and when he made his historic post-11 September address to Congress less than two hours later.

When I first saw him, he was a bag of nerves, his face twitching from nervous tics; by the time he appeared before Congress and a huge television audience, he seemed confident and calm. What had he ingested in the meantime, and was the White House doctor, Colonel Richard J Tubb, involved or not?

I mention all this to show how fevered this election campaign is becoming. The Bush side especially shows no hesitation in smearing its opponent, both personally and politically. The right-wing Sinclair Broadcasting Group - which reaches a quarter of Americans via its 62 television stations - is now planning to pre-empt regular programming to show an hour-long diatribe against John Kerry, called Stolen Honour. Twelve of the television stations are in swing states, and the "documentary" - in which Kerry is accused of "treason" - will be screened between 21 and 24 October.

I counted seven recent polls, and all but one show Bush with a slight lead over Kerry; the other, from Zogby, has both candidates equal on 45 percentage points each. Ralph Nader does not score more than two points in any of the polls, but if the election proves as close as the polls suggest, that could still be enough to scupper Kerry's chances.

The outcome of the election probably rests on eight swing states: Colorado, New Hampshire, New Mexico, Iowa, Minnesota, Pennsylvania, Ohio and Florida. Of these, Pennsylvania, Ohio and Florida are the most crucial, with 68 electoral college votes between them; the candidate who wins two out of three of these states will probably win the election. Kerry is very slightly ahead in polls in Pennsylvania and Ohio, while Bush has a clearer lead in Florida. There is also a "challenger" trend in US politics, whereby most of the undecided vote - currently running at 4 per cent - goes to the challenger rather than the incumbent.

I still do not know why Bush blinked so furiously in the second presidential debate, or why he said "let me finish" in the first - the one where he was supposed to have been wired - when nobody was trying to interrupt him. I suspect he is both depressed and stressed.

He has had more problems than usual finding the words he wants. He seems to be less mentally adroit than he was when he first campaigned to be governor of Texas ten years ago, or even during the 2000 campaign against Al Gore.

Perhaps it is just election fever that is making Bush behave in this way, but I have to say that his public behaviour is increasingly erratic. The implosion I have spoken of always seems about to happen. He may still just make it on 2 November, however - in which case, we will face the prospect of four more years in which we will be able, at our leisure, to psychoanalyse the world's most powerful man.