At the University of Notre Dame, political scientist David Campbell thinks Biden's riches-to-rags background is a key part of the narrative. "The image of the working-class Catholic is part of the American ethos, featured in movies and literature," Campbell says. "People can relate to this an as archetype. Obama's biography doesn't fit into any categories. We don't have a half-Hawaiian, half-Kenyan, has-lived-all-over-the-world category."