The Negative Campaigning Comparative Expert Survey Dataset (NEGex) also contains information about the personality traits of a wide palette of candidates having competed in the elections surveyed since 2016.
Some of the findings of my research on the personality of candidates are:
Populists score lower on agreeableness, emotional stability and conscientiousness than mainstream candidates (ref)
Populists score higher on extraversion, narcissism, psychopathy and Machiavellianism than mainstream candidates (ref)
Donald Trump has an "off-the-charts" personality profile: very high extraversion and Dark Triad traits (narcissism, psychopathy, Machiavellianism), and very low agreeableness, conscientiousness, and emotional stability (ref)(ref)(ref)
Candidates high in agreeableness and openness tend to be associated with campaigns that are less negative and harsh, but more based on positively valenced appeals (ref)
High conscientiousness and psychopathy seem associated with better electoral results, whereas extraversion could be counterproductive (ref)
The Dark Triad is associated with more negative campaigns and the use of fear appeals (ref)(work in progress)
Nai, A. (2019). The electoral success of angels and demons. Big Five, Dark Triad, and Performance at the Ballot Box. Journal of Social and Political Psychology, 7(2), 830–862.
Nai, A., & Maier, J. (2019). Can anyone be objective about Donald Trump? Assessing the personality of political figures. Journal of Elections, Public Opinion & Parties. doi: 10.1080/17457289.2019.1632318
Nai, A., and Martinez i Coma, F. (2019). The personality of populists: Provocateurs, charismatic leaders, or drunken dinner guests? West European Politics, 42(7), 1337-1367.
Nai, A., Martinez i Coma, F., and Maier, J. (2018). Donald Trump, populism, and the age of extremes: Comparing the personality traits and campaigning style of Trump and other leaders worldwide. Presidential Studies Quarterly, 49(3), 609–643.
Disagreeable narcissists, extroverted psychopaths, and elections: A new dataset to measure the personality of candidates worldwide. European Political Science, 18(2), 309–334.Nai, A. (2018).
Nai, A., and Maier, J. (2018). Perceived personality and campaign style of Hillary Clinton and Donald Trump. Personality and Individual Differences, 121: 80-83.