With Barack Obama's resounding victory in the Iowa Democratic caucus, Hillary Clinton's presidential nomination no longer looks so inevitable. Indeed, if Obama can follow through with a victory in the New Hampshire primary next week, he will replace Clinton as clear favourite for the Democratic nomination. Watching Obama's victory speech, it is hard not to be impressed, even inspired:

He is a remarkable speaker – more reminiscent of the presidents of Hollywood blockbusters than of the incumbent – and his appeals to hope, change and unity are what have brought so many young people, independents, and even disillusioned Republicans to the polls in his favour.

But being a good president requires more than just rhetoric, and now that Obama is no longer an underdog, he will need to firm up his policy positions if he wants to make it all the way to the White House. That said, he would be a very tough candidate for the Republicans to beat. A Hillary nomination would give them a much better chance of hanging on to the White House.

US politics is going to be fascinating to watch in 2008.