Similar Moral Values, Different Agendas? U.S. Politicians’ Use of Moral Language Is Issue-Specific

What moral values do politicians on the right and left invoke in their rhetoric, and do they emphasize different issues when appealing to these values? We used Structured Topic Models (STM) combined with a word embedding model to examine U.S. politicians’ use of moral language and identify the issues Democrats and Republicans moralize most on Twitter (X). Analyzing 1,578,057 posts from U.S. members of Congress (2019–2023), we found that (1) their overall use of moral language was not influenced by ideology as predicted by Moral Foundations Theory (MFT) and (2) they moralized different issues within each moral foundation. For example, Republicans invoked the care foundation to criticize Democratic economic policies, whereas Democrats used it to highlight the harm caused by Trump’s immigration policies. These findings suggest that politicians’ use of moral language may be driven more by the relevance of the issue to their party than by ideology alone.