Washington - The 2008 presidential campaign has been one of the longest in US history, spanning nearly two years, and the most expensive, totalling about 1.5 billion dollars spent by 20 candidates during the primary and general elections.
US President George W Bush was barred by the constitution from seeking a third term, and Vice President Dick Cheney was not interested, making the race the first "open" presidential election campaign since 1952.
January 20, 2007 - Senator Hillary Clinton, 59, the former first lady, announces a widely-favoured bid for the Democratic nomination.