The transition towards more renewable energy will substantially increase voters' involvement in the political decision-making process in the energy domain. Decisions such as whether to approve or reject large-scale energy programs can be complex, especially when available information cues are numerous and conflicting. Here, we hypothesize that political ideology is a strong determinant in this process, serving as a filter that voters apply when evaluating the relevance of provided information cues. We tested this hypothesis in the context of the 2017 Public Vote on the Swiss Energy Act. A sample of n = 931 Swiss voters were presented with arguments in favor or against the Energy Act, which were framed in terms of values found to be relevant for liberal and conservative ideologies, respectively. Political ideology strongly determined individual attitudes and voting preferences. Political ideology moreover moderated the influence of information provision on decisions, in that arguments congruent with voters' political ideology were more likely to be evaluated as personally relevant and integrated into their decisions. We discuss the implications of our findings for measures on how to address ideology-based decision-making in order to ensure a well-informed electorate.