One of the reasons American presidential elections are such compelling narratives is that they feature, almost as if by design, every trick in the book of classical dramaturgy.

Even in the dullest campaigns, the story lines of a presidential election follow a trajectory that could have been devised by Aristotle or executed by Shakespeare — great moral lessons, the interplay of complex and simple characters, the large themes of human emotion and desire and, of course, the myriad little plot developments that sustain the audience’s attention.

One such twist that unfolds without fail every four years is the Mystery of the Stolen Campaign Document. This can take many forms — lists of wealthy fundraisers left on planes; detailed polling reports found on stray laptops; prep notes for campaign debates that mysteriously show up in the other candidate’s dressing room hours before the big event.

This week we have already had the first big document capture of the 2008 campaign. The New York Daily News got hold of a 170-page dossier that outlines the planning for a putative presidential campaign by Rudolph Giuliani, the former mayor of New York.

Have you noticed, by the way, that “dossier” is one of those words, like “probe” and “aide” that only ever really appear in newspaper articles? Do not be surprised in coming days if, after an investigation of the former mayor’s assistants, someone comes up with the headline “Giuliani Aide in Dossier Probe”.

In any case the document discovered in a hotel room outlines, with reliable clarity, the hopes and fears of a Giuliani campaign team as he ponders a run for the Republican nomination to succeed George Bush.

A Giuliani candidacy for president has been one of the most talked-about political prospects almost from the day the twin towers fell. Images of the stoical, unwearied mayor, his face caked in grime and etched in tragedy became a symbol of that day and an instant metaphor for real leadership in the face of unimaginable horror.

Though 9/11 was his finest hour it is not his only claim on larger political office. As mayor for eight years, whose name is synonymous with the zero-tolerance approach to urban crime-fighting, Mr Giuliani is generally credited for the sharp reduction in serious crime in New York in the 1990s.

If that was all there was to Mr Giuliani, the race for the Republican nomination would be over already. Early opinion polls certainly suggest he is highly popular.

But as Aristotle or Shakespeare could tell you, heroes are always more complex than that. Should Mr Giuliani run, his opponents and the national media will ensure that his flaws receive plenty of attention.

His biggest political problem is that he has views that do not conform to modern Republicanism — a big obstacle in a primary contest where candidates must first win the votes of their own partisans. He is firmly in favour of abortion rights, gay marriage and embryonic stem-cell research.

The Giuliani strategy for neutralising this problem seems to be an uneasy combination of tilting gently towards the right in his most recent public statements on these subjects, while championing a form of libertarian conservatism. This is an honourable but somewhat lost political philosophy in America that says government should confine itself to defending its citizens from internal and external threats and otherwise get out of their lives. It may be due for a political comeback, especially as the public seem to be tiring of the hectoring certainties of evangelical conservatives.

But even if Mr Giuliani can pull this off, he faces other formidable challenges. He has what is generally described, in one of the more overworked euphemisms of the age, as a “colourful” private life. He has had three marriages, the latest after a spectacularly public divorce from a New York actress. He has also displayed an unsettling penchant for eyebrow-raising acts of self-publicity, including the memorable occasions when he appeared dressed as a woman on late-night television.

This is the peril of the choice Mr Giuliani offers Republicans — you pay for the terrorism-defying, patriotism-stirring, crime-scourging hero of the world’s greatest metropolis, and you get a cross-dressing, wife-cheating, abortion-supporting denizen of America’s nearest equivalent to Sodom.

Other factors work against Mr Giuliani, too. The drama of 9/11 obscures but cannot hide the fact that his sole experience in elective public office has been the administration of a large city. No one has been elected US president without at least some experience of state or national office or service in the military.

Perhaps to plug that gap, he has cast himself as a strong supporter of President Bush’s foreign policy, a move that may not look wise by the time the election campaign gets under way in earnest. At a time when national security dominates political debate, Mr Giuliani’s evident inexperience could hurt him.

The former mayor also has to consider, as all potential candidates do, the personal cost of running for president. In his case this can be measured not just in the intolerable public scrutiny of his lively private life, but in a serious loss of earnings.

As a prosecutor and then as mayor, the talented Mr Giuliani has spent most of the past 25 years on a government salary. His fame after 9/11 catapulted him instantly into the most lucrative echelons of global public speaking and consulting.

He can command $100,000 a speech these days (as well as other perquisites, such as private charter aircraft to ferry him and his entourage to glamorous conference destinations). Giving up annual earnings of millions of dollars for a campaign for public office that may end up scraping large chunks of the gilt off his reputation would require real confidence that he can win.

His advisers say the former New York mayor will decide in the coming weeks whether to take that gamble. His candidacy would make for one of the best political plot-lines in an already absorbing piece of electoral theatre. Which could be the best reason why he may be better advised to watch from the audience as the drama of 2008 unfolds.

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