As demonstrated by the COVID-19 pandemic, many political decisions involve a high level of uncertainty. Policy outcomes are thus subject to chance. However, when evaluating the past performance of politicians, voters tend to focus on policy outcomes rather than on the political decisions and the circumstances under which they were taken, leading to less than optimal voting decisions. In this study, we examine this so-called outcome bias and its effect on the delegation process. In an online experiment, subjects assigned the role of a politician decide how much to invest in a risky policy, whereas subjects assigned the role of a voter decide whether to re-elect the politicians based on the politicians’ decision and the outcome. The treatments, which vary potential reward and risk of the policy, allow us to derive causally whether the probability of success affects (I) voters’ preferences for political delegates or trustees in decisions taken under uncertainty, (II) the magnitude of voters’ outcome bias, and (III) politicians’ responsiveness to voters’ risk preferences and biases. Considering the outcome bias, in some instances it may be better for politicians to disregard voters’ risk preferences and focus on the sheer probability of policy success. In this manner, the study provides novel insights into the role of risk and risk preferences in representative democracies.