Why are electoral winners more willing to support democratic norm violations? Using a mediator blockage survey experiment in the United States, I find that winners endorse norm erosion due to heightened in-party favoritism following their party’s electoral victory. The experiment successfully manipulated in-party favoritism, the mediator, demonstrating that respondents exposed to a winning signal, suggesting their party is likely to secure both the presidency and control of Congress, exhibit greater in-party favoritism. This increase significantly predicts a greater tendency to perceive norm-eroding policies, such as banning protests or disqualifying candidates, as democratic and to support these policies. Additionally, winners are less likely to evaluate these policies through a lens of strategic political calculation, that is, whether these policies benefit their party directly or indirectly, challenging the prevailing view that winners tolerate norm violations for instrumental reasons.
