Dark tetrad traits in politicians and voter behavior: Joe Biden and Donald Trump in the 2020 presidential election

• Both Biden and Trump were attributed significant dark tetrad traits (DTTs)—Machiavellianism, narcissism, and psychopathy. • Trump was perceived as more narcissistic, psychopathic, and sadistic than Biden. • DTTs were related to voting willingness, modified by political views, trait intensity, and DTTs seen in an opponent. • Darker DTTs (psychopathy/sadism) decreased voting willingness; lighter DTTs (narcissism/Machiavellianism) were beneficial. • Perceived DTTs in an opponent had a stronger impact on willingness to vote than those attributed to a preferred candidate. While the erosion of democracy is often tied to specific political figures, not many studies have examined how perceived aversive personality traits in politicians relate to voter behavior. In our study ( N = 456), we investigated how dark tetrad traits (DTTs) − subclinical Machiavellianism, narcissism, psychopathy, and sadism − observed in presidential candidates Biden and Trump related to potential voters’ willingness to support them. Both candidates were perceived as exhibiting significant DTT levels, except Biden showed average everyday sadism. Trump was seen as higher on most DTTs compared to Biden, except for Machiavellianism. Trump was predominantly characterized as narcissistic, sadistic, psychopathic, and Machiavellian, while Biden was viewed as mostly Machiavellian, narcissistic, and psychopathic. Perceptions correlated with political orientation, showing ingroup favoritism. Democrats attributed dark triad traits—especially narcissism, psychopathy, and sadism—more to Trump than Biden, whereas Republicans viewed them more homogeneously. Importantly, DTT attributions associated with voting willingness accounted for substantial variance. However, this relationship was nuanced: political favoritism impacted results, with e.g. Trump’s narcissism increasing Republican’s but decreasing Democrat’s voting intention towards him; trait severity mattered, with lighter narcissism and Machiavellianism more accepted than darker psychopathy and sadism; asymmetry existed, with Biden’s narcissism viewed positively regardless of political orientation but in Trump’s case it did not; and an opponent effect occurred where DTTs mattered more as seen in un unfavored candidate. The modified SD4 scale proved psychometrically sound for measuring politician DTTs. The findings underscore the importance of investigating such traits in politicians, especially during 2024—a global election year.