Elite political incivility is rising across democracies

Is political incivility rising across democracies - and if so, why? Analysing approximately 13.8 million tweets from parliamentarians in 26 countries with a validated large language model, we find that the share of severe incivility nearly doubled between 2017 and 2022, from $\approx$2.7% to $\approx$5.8% of tweets. Populism is the strongest party-level predictor (OR~=~1.46, 95%CI: 1.29--1.65), and its association with incivility is amplified in opposition. Stronger liberal democracy is associated with lower severe incivility (OR=~0.84 per SD, 95%~CI: 0.72--0.98). The rise in incivility is overwhelmingly behavioral - party families across the spectrum becoming more aggressive - rather than compositional: the growing prominence of radical parties explains little of it. Nationalist and radical-right parties remain the most uncivil throughout, but the gap narrows as their 2020 peak partially recedes while mainstream parties become steadily more uncivil. Together, these findings point to a mainstreaming of incivility: aggressive and demeaning rhetoric is becoming increasingly common across the political spectrum, with implications for public trust and democratic resilience.