Combating corruption remains a central problem for many governments. Disillusionment with corrupt officials can lead voters to turn their backs on democracy and lure them toward supporting authoritarianism. In collaboration with two major political parties in North Macedonia, we conduct a field experiment that exposes citizens to parties’ anti-corruption agendas. We explore whether cross-party anti-corruption platforms have stronger effects than anti-corruption platforms from a single party on citizens’ behaviour and attitudes. Our results imply that opposition parties should be brought into anti-corruption initiatives alongside ruling parties to decrease corruption and sustain voters’ support for democratic rule.