Polarization is increasing not only among political parties adherents, also intraparty polarization between ideologically extreme and ideologically moderate partisans is on the rise

Intraparty Polarization in American Politics. Eric Groenendyk, Michael W. Sances, and Kirill Zhirkov. The Journal of Politics, Aug 27 2019. https://www.journals.uchicago.edu/doi/abs/10.1086/708780. Free https://kirillzhirkovme.files.wordpress.com/2019/09/groenendyk_intraparty_polarization.pdf

Abstract: We know that elite polarization and mass sorting have led to an explosion of hostility
between parties, but how do Republicans and Democrats feel toward their own respective parties? Have these trends led to more cohesion or more division within parties? Using the American National Election Studies (ANES) time series, we first show that intraparty polarization between ideologically extreme and ideologically moderate partisans is on the rise. Second, we demonstrate that this division within parties has important implications for how we think about affective polarization between parties. Specifically, the distribution of relative affect between parties has not become bimodal, but merely dispersed. Thus, while the mean partisan has become affectively polarized, the modal partisan has not. These results suggest polarization and sorting may be increasing the viability of third party candidates and making realignment more likely.

Keywords: Polarization, Party Coalitions, Realignment, Ideology