By Richard Downes, Washington Correspondent,  in Iowa

So after a pedestrian campaign that hadn’t caught alight, finally the American Presidential marathon is underway with a bit of pizzazz and a razor thin win for Mitt Romney.

He hadn’t done much campaigning here in Iowa. The conventional wisdom was that this is such a conservative state that he didn’t stand much of a chance.

Surely one of the tough right-wingers would come along and capture the hearts of the caucus goers? Rick Santorum did but he didn’t win.

Romney now travels to what is virtually his home state with a spring in his step and that crucial commodity, so beloved of American politics: momentum.

And what of the others?

The one-time darling of the conservatives, Rick Perry, has gone back to Texas to lick his wounds and reassess his campaign.

He’s a goner and Michelle Bachman is giving up the ghost too.

The field has narrowed dramatically and the New Hampshire primary will provide further evidence of who can make the grade.