Which human activity, other than the necessities of life, like eating, sleeping and shopping, are most people involved in? Politics, in its broadest sense. Politics, not racing, is the true sport of kings, which is why kings monopolised it for so long. Politics has been called showbusiness for ugly men. Even that is changing. A good head of hair, a firm chin and a facelift can be an advantage. Just as Hollywood dominates the world's fashion media, so Washington dominates worldwide political fashion. That is another reason why US politics fascinates us all. But like any sport, anything can happen in the last 10 minutes. This brings me, of course, to the US presidential elections in November and the fascinating race among Democrats to find an opponent for George W. Bush. The United States is a hyperpower unmatched in world history. Everything it does impacts on everyone. US growth pulls and lifts the global economy; its excellence in research and development into new drugs gives hope to sick people everywhere. Its military spending matches that of the next largest 15 to 20 nations put together. When Mr Bush gave his State of the Union address, TV reporters asked people in Iraq, France, China and Mexico for comments. When my country, New Zealand, makes a mistake, we are a danger only to ourselves. When the US makes a mistake, everyone is affected. That is why we need to understand the US. Like any other product, craze or fashion, US political ideas and opinions impact on other countries. The latest technology, ideas and systems are always tried out in the most sophisticated markets first. A loss for Mr Bush would have a ripple effect against conservatives everywhere. This is not new. The presidencies of John F. Kennedy and Lyndon Johnson helped progressive parties implement their social and economic programmes around the world. In the same way, a generation later, the Reagan presidency raised a basic question of the role of government elsewhere in the world. From a leftist standpoint, what lessons can be learned from the US Democratic primaries? They are being driven by a furious and focused hatred of Mr Bush, matched by a pragmatic determination to replace him. In the minds of US Democrats, there is only one question - who can oust him? Principles, policy and personality only matter if they serve the ultimate purpose of regaining the White House. The aloof, patrician Senator John Kerry, who looks like the priest from The Exorcist, summed it up in Iowa when he declared: 'Don't send a message to Washington, send a president.' The plain-spoken former governor, Howard Dean, was ahead in party polls. His furious attacks on Mr Bush won him early applause. At last, a real Democrat. The party faithful loved it when he declared that he was from the 'Democratic wing of the Democratic Party', and scorned Washington Democrats as being 'Republican-lite'. Mr Dean's rant on Iowa election night may have sunk him. The master of the internet became its victim as video footage of his speech spun through cyberspace. Exciting the true believers is not the same as winning the country. The party faithful are not dumb, and their main goal is to exorcise Republicans from the White House. They see the Bush administration as extremist, dominated by neo-conservatives who are a far cry from the gentler Republicans personified by George Bush Snr, the centrist Dwight Eisenhower or even Richard Nixon. To many hardcore Democrats, even Ronald Reagan seems moderate in comparison. Mr Dean has created a climate where it is now acceptable to attack a president who has been superb at portraying himself as above the political fray, putting the needs of the country first. Of course, saying that you are non-political is the oldest political trick in the book. Senator John Edwards looks like promising vice-presidential material, with his uncanny impersonation of Bobby Kennedy, down to the finger-jabbing and distinctive hairstyle. He will struggle to win the big prize if he fails to win the South Carolina primary and the other southern states. The US is not like other countries. More people own businesses than are members of trade unions. More people own shares - or watch the Super Bowl - than vote. There is more than one America. The clash of values, even civilisations, within America is profound. In terms of values, California, the New England states and the south and midwest are different worlds. For centuries, American thinking and politics were driven from the northeast. Boston and New York, in terms of influence, wealth and congressional seat numbers, were the epicentre of American power. But that picture has changed with the growth in the sunshine states and the South. While the Democrats are in the race, never underestimate Mr Bush and his fiercely competitive team. Much has been said about the Florida recount in 2000, but it would never have been an issue if Al Gore had won former president Bill Clinton's home state of Arkansas and his own state of Tennessee. Great national interests do not change with elections, which is reassuring when trying to work out what it all means. Mike Moore, a former prime minister of New Zealand, was the first director-general of the World Trade Organisation