The study analyzes the decision-making process in foreign policy, examining the governments of the Workers Party in Brazil and the Socialist Party in Chile, investigating how international acts may be the object of legislative and partisan action and, most important, that is subjected to conflict/consensus between government and opposition. Considering the foreign policy as a public policy, the methodological assumption of this study assumed that political parties are important actors in the decision-making process, acting as veto players and influencing international acts from ideological variables and composition of coalitions.