In recent decades Iowa has seen almost no demographic change. Ninety-one per cent white, it was one of a handful of states where Barack Obama won a majority of white voters four years ago. But many of the blue-collar white voters who have traditionally voted Democratic in the eastern part of the state are increasingly attracted to Trump.

In fading factory towns like Dubuque and Waterloo, long bastions of Democratic support, Trump’s anti-free trade and anti-immigration message is increasingly finding an audience.

In the suburbs of Des Moines and Cedar Rapids, meanwhile, he is not losing many moderate Republicans – mostly because such areas are home to significant numbers of evangelical Christians, to whom Clinton is simply anathema. If such voters do not vote for a third party candidate or stay home, Trump will be their man.

New Trump supporters have however presented new challenges. Traditionally, Republican operatives scorn Democratic campaigns, which tend to be based on hiring hundreds of staffers to go door to door, getting marginal voters to sign up for absentee ballot requests. Republican voters have been far more consistent, meaning the party’s campaigns have instead focused on tapping into networks of social conservatives, in particular home-schoolers.