“How Politicians Polarize reveals a divide between what politicians do and what people truly want. While Americans themselves reject animosity, Costa shows the process by which politicians are nevertheless rewarded for negative attacks. Her multi-method account offers both assurance that Americans disdain this 'othering' but also a dark warning for how negative representation becomes a dominant strain within US politics.”

Samara Klar | coauthor of "Independent Politics"

“How Politicians Polarize reveals how the modern political rhetoric of us versus them, of this group against that group, shapes how we are represented. Negative partisanship has been the hallmark of American politics over the first three decades of the twenty-first century. Costa shows us why and how our representatives create and sustain that as a matter of political strategy, despite voters wanting to hear more about what representatives will do to address real problems. A must-read.”

Stephen Ansolabehere | Harvard University

“How Politicians Polarize offers a path-breaking shift in our understanding of representation. It introduces negative representation: when elites focus on opposing the other party rather than advancing policy on behalf of their constituents. Costa’s wide-ranging examination reveals how this pernicious practice stems, not from voters’ preferences, but rather from the media ecosystem, non-competitive elections, progressively ambitious politicians, and partisan misperceptions. Costa offers remarkable insight in explaining that a ‘way out’ would be privileging voters’ desires over perceived systemic incentives.”

James N. Druckman | coeditor of "Partisan Hostility and American Democracy"