The framing impact of political discourses has long been attested for. Metaphors in particular are known to ease the understanding of complex concepts and processes. Yet, the question remains to what extent metaphors do work the same on different recipients? Based on an experimental design, we test a potentially key moderating variable in the study of political metaphors: political knowledge. Our experiment aims at determining the extent to which the confrontation of individuals to arguments and metaphors impacts their preferences regarding the implementation of a basic income in Belgium. In particular, we hypothesize that the marginal effect of metaphors as cognitive shortcuts decreases when political knowledge increases. Our findings suggest that some metaphorical frames are more successful than others, hereby supporting the idea that the aptness of the metaphorical frame is a key factor when conducting experiments. We conclude that political knowledge is an important variable when analyzing the framing effect of metaphors, especially when it goes about very low or very high levels of political knowledge. The insertion of metaphors in political discourses may easily succeed in rallying individuals behind a given cause, but this would only work if participants have a lower knowledge of politics.