Effective policy-making requires parties to accept political compromise, yet doing so likely affects their reputation. Political parties thus face a trade-off between responsibility and responsiveness. Responsibility calls for parties to broker compromises, while responsiveness requires parties to adhere to their original policy positions. Previous research has shown that voters adjust their perceptions of parties in response to compromise and party policy change. It is not clear, however, how voter perceptions of compromise affect political trust and credibility. We address this question with two pre-registered studies. With an observational study of 6 Western European countries (Study 1), we show that rejection of compromise coincides with lower levels of trust in political parties. To examine more closely whether responsive or responsible party behaviour in coalition negotiations is decisive for voters’ party evaluations, we conduct survey experiment in Germany (N=7000) fielded just after the 2021 parliamentary elections (Study 2). Using simulated Instagram party messages as treatments, we 1) isolate the effect of parties’ negotiation position from success or failure in the negotiations; and 2) delve into the psychological determinants that drive voters’ party trust after (not) accepting compromises. We find that parties’ steadfast positioning (i.e. rejecting compromise) in coalition talks leads to higher evaluations of party trust, credibility, and representational quality. Further, we find that respondents’ psychological traits of being principled and high social distrust negatively affect their acceptance of party compromise. Our study has important implications for the study of political representation by shedding light on the reputational costs of political compromise.