Why do political parties choose to refuse elections? Even after some decades after democratic transition, boycotts and protests are still common in Latin American elections. Beyond the ongoing process of institutionalization, common to all countries in the region, this paper argues that the variable trust in the robustness of electoral governance procedures can explain the choices of political competitors among the alternative strategies: boycott, protest or compliance. Among several features of electoral governance, partisan power sharing in electoral management has been a target as both a problem and a solution for electoral integrity issues. Once sharing power in electoral management bodies, political parties may watch each other producing confidence or may take advantage to favor themselves. Previous studies have shown that partisans electoral governance is a necessary condition for post-electoral protest from opposition parties and also that it has significant effects on the trust in electoral fairness. Now this paper advances in that research agenda to test a hypothesis about the mechanism of that relationship: losers choose to refuse results when they know that the trust in the robustness of electoral governance is low, so their complaints will be believed. The paper argues that ceteris paribus, there is a causal chain linking (i) vulnerable models of electoral governance (particularly partisan management), (ii) trust on the fairness of elections and (iii) the strategies of political actors. Institutional vulnerability to electoral fraud and manipulations makes the complaints of political parties potentially more plausible before public opinion because in new democracies some models of EMBs are usually viewed as biased and discretionary. The general distrust in vulnerable models of electoral governance would perhaps increase the chances of a party denouncement get public support, without which would be too risky to call a post-electoral protest. The paper uses a large-N research design in a dataset with elections in 18 Latin American countries since redemocratization and electoral governance data in a multivariate multilevel model.