To outsiders, they looked like simple stacks of paper. But for Donald Trump's first presidential campaign, they represented a missed opportunity.
A month before Iowa's 2016 presidential caucuses, mountains of so-called pledge cards sat in the corner of Trump's suburban Des Moines state headquarters. They contained the names and contact information of roughly 10,000 Iowans who attended Trump campaign events and responded by returning the cards suggesting they were open to backing the reality television star who was now seeking the White House.
