All by Himself? Trump, Isolationism, and the American Electorate

During his campaign and subsequent presidency, Donald Trump staked out and implemented an isolationist foreign policy agenda that sought to put "America First" and curtail U.S. participation in international treaties and trade agreements. Isolationism represented a dramatic turn away from the internationalism of all postwar presidencies, and Trump's radical foreign policy changes raise two novel questions: Did isolationism resonate with American voters, and if so, how did this shape the outcome of the 2016 presidential election? We analyze how attitudes toward isolationism changed in the American electorate from 1992 to 2016, and whether aggregate changes in isolationism conferred any electoral advantages on Trump in 2016. The results indicate that while isolationism tends to be supported by a relatively small portion of the electorate, aggregate levels of support increased noticeably in 2016. Controlling for established factors, particularly partisanship, isolationism disposed voters to support Trump's candidacy. These two developments delivered a measurable benefit to Trump, one that is of theoretical significance in going beyond partisanship to influence both Democratic and Republican identifiers. Future shifts in levels or political relevance carry with them a potential to shape elections and policy-making. We discuss implications of findings for scholarship in political behavior and political sociology.