By Richard Downes, Washington Correspondent, in Iowa

On the frozen fields of 100 counties, the candidates are trying to get voters to remember their name in the frantic last hours before they finally cast a vote.

Or do they ever really cast a vote?

The caucus system is an arcane and strange one and unique to a few states.

The party faithful (and anyone who decides they want to become a republican on the night!) sit around and listen to presentations by the main candidates.

They then write their preference down on paper and the winner’s name is phoned into the central election HQ here in Des Moines.

It is not exactly rocket science or even very high tech, but it does do what is intended: the nuanced preferences of a diverse but conservative state are recorded for the national party to take note of.

No one wins from Iowa but plenty of people die out here.

The Iowa caucuses can give a candidate a bit of a push but is not a great predictor of the final outcome and rarely useful in saying who will become President.

It does however kill off the campaign of many candidates and this year looks like being no exception.

Little Iowa, with only slightly more than three million voters kicks off the presidential contest with a bang.