Pre-existing research demonstrated that voters’ perceptions of leadership traits impact overall candidate evaluations. This literature focuses primarily on politically relevant traits: competence-related traits, or character traits associated with leadership performance. Less is known about the impact of candidates’ personality traits, and especially the “darker” ones (narcissism, Machiavellianism, psychopathy). It is yet unclear to what extent the (perceived) presence or absence of dark personality traits in candidates influence public attitudes towards them - and to what extent this effect exists above and beyond the structuring role of partisan attitudes. To answer this question, this study uses a multi-method approach combining an experimental design and a post-electoral survey on the 2020 US Presidential election. The survey data (study 1) confirms the key role of partisanship as a driver of candidate perceived personality. The experimental evidence (study 2) confirms a causal relationship between (perceived) candidate personality and subsequent evaluation: exposure to a negatively (positively) framed candidate personality reduces (increases) candidate likeability, and that effects of (perceived) presence of darker traits are larger than the effects of their (perceived) absence. Across both studies, the results confirm the relevance of dark triad personality traits for candidate favourability, and the existence of asymmetric effects for presence vs absence of dark traits.