Politicians with large media visibility and social media audiences have a significant influence on public discourse. Consequently, their dissemination of misinformation can have profound implications for society. This study investigated the misinformation-sharing behavior of 3,277 politicians and associated public engagement by using data from X (formerly Twitter) during 2020-2021. The analysis was grounded in a novel and comprehensive dataset including over 400,000 tweets covering multiple levels of governance-national executive, national legislative, and regional executive-in Germany, Italy, the UK, and the USA, representing distinct clusters of misinformation resilience. Striking cross-country differences in misinformation-sharing behavior and public engagement were observed. Politicians in Italy (4.9%) and the USA (2.2%) exhibited the highest rates of misinformation sharing, primarily among far-right and conservative legislators. Public engagement with misinformation also varied significantly. In the USA, misinformation attracted over 2.5 times the engagement of reliable information. In Italy, engagement levels were similar across content types. Italy is unique in crisis-related misinformation, particularly regarding COVID-19, which surpassed general misinformation in both prevalence and audience engagement. These insights underscore the critical roles of political affiliation, governance level, and crisis contexts in shaping the dynamics of misinformation. The study expands the literature by providing a cross-national, multi-level perspective, shedding light on how political actors influence the proliferation of misinformation during crisis.