Despite the growing literature on morality in politics, it is unclear whether political parties' moral rhetoric are persuasive to voters who do not support them. In particular, can moral rhetoric increase non-copartisans' favorability toward the party? Drawing insights from previous research on moral arguments and partisan bias, I argue that moral rhetoric is generally not persuasive, even among those who are morally aligned, and that moral rhetoric can further push away non-copartisans with pre-existing hostility toward the party. I use original survey experiments on representative samples from Britain to test my arguments. Consistent with expectation, I find that moral rhetoric does not easily persuade. Inconsistent with expectation, I find that moral rhetoric does not further alienate hostile non-copartisan voters. These findings suggest the limit as well as the potential of moral rhetoric as a form of party communication. The paper contributes to studies in party competition, moral psychology, and persuasion.