Populism, Partisanship, and Protection: Elite Rhetoric and U.S. Public Opinion on NATO

Abstract The rise of populists across the globe has caused increasing alarm about the continued functioning of security alliances. This is particularly true for the United States and the North Atlantic Treaty Organization (NATO), with populist President Donald Trump repeatedly disparaging the alliance since his 2016 campaign. Yet, we know very little about how populism influences support for alliances, particularly in the context of the United States. Here, we examine the impact of populist messaging on U.S. public opinion toward NATO. First, using observational data from the 2020 American National Election Studies Time Series Survey, we find that NATO support is correlated with populist sentiments. We investigate this connection further by using an original survey experiment in which we test two different negative-NATO populist frames and their impact on U.S. public opinion concerning support for NATO. We find clear evidence that populist attitudes are negatively associated with affect toward NATO, and we find partial support for our primary causal hypotheses about the effect of populist rhetoric on support for NATO. Finally, we find evidence of clear conditional partisan treatment effects of populist criticisms of NATO, with Democratic respondents consistently being more responsive to populist messages that erode support for NATO.