This dissertation addresses the different ways in which Americans define citizenship and nationhood and the associated implications for politics and political rhetoric. I argue that the contesting of the national identity--the ways in which a given image of the United Sates is privileged over other images of the nation--is central to the ideological divisions of the United States today. The dissertation begins by examining existing scholarship on the nature of ideological divisions and arguments in contemporary US politics, and the survey demonstrates that each of these approaches tells us a great deal about how certain individual factors influence ideological arguments, but these insights tend to come at the cost of minimizing the roles played by extremely powerful societal forces like race, ethnicity, gender, religion, and sexual orientation. I propose, therefore, a view of the left-center-right political spectrum in the United States as a spectrum based on competing--and sometimes overlapping--nationalist ideologies, with opposing groups competing for control of the state agencies that sustain and diffuse the national high culture. According to this view, individuals define their position in the ideological spectrum based on whom they culturally identify with, and practitioners of political rhetoric would benefit from identifying the culture of their ideology with the American "mainstream." Toward this end, the dissertation draws on nationalism theory to establish a theory to examine how competing national identities are contested both in political rhetoric and in popular media that is not explicitly political. The dissertation then concludes by identifying rhetorical strategies that have been effective at crossing ideological lines in the past and proposing new strategies that can be effective at crossing ideological lines in the future.