The Affordable Care Act and Polarization in the United States

We argue that partisan polarization in public support of the Affordable Care Act (ACA) is affected not only by policy design but also by which party makes those decisions. Using an innovative dataset that measures state-level quarterly ACA support from 2009 through the start of the 2016 presidential election, we find that opinions toward the ACA are less polarized in states with misaligned partisan environments where Republican governors support Medicaid expansion. We also find evidence that Republican opposition intensifies when a Democratic governor supports expansion. We do not find consistent evidence of such patterns for governors' positions on state health insurance exchanges. Our research sheds light on a key aspect of how health policy preferences respond to shifting political contexts in a polarized, federated polity.