US: Presidential candidates flock to Iowa state fair Former Massachusetts governor Bill Weld, the only Republican challenging US President Donald Trump to represent the party in the 2020 presidential election, takes to the stage at the Iowa state fair. Presidential candidates campaign for months in this rural state, the first to hold a caucus during the US primary season. The state fair represents an opportunity to reach out to voters for smaller candidates such as billionaire Tom Steyer. IMAGES AND SOUNDBITES