AbstractThe international election monitoring regime has become considerably more complex in the twenty-first century. Although the number of organizations engaged in high-quality election monitoring has plateaued, the number of low-quality monitors—commonly known as zombie monitors—has continued to grow. Low-quality election monitors threaten democracy because they validate flawed elections and undermine the legitimacy of the international election monitoring regime. This article argues that international politics have played a crucial role in the diffusion of low-quality election monitors. It hypothesizes that ties with autocratic powers that promote low-quality observers and membership in authoritarian regional organizations significantly increase the likelihood that a country will host low-quality monitors at its elections. To test the hypotheses, the article draws on original data on international election observation between 2000 and 2020 that identifies the most comprehensive set of groups of election monitors to-date. A statistical analysis of the dataset supports the argument.