What motivates citizens to donate to political campaigns? The literature has characterized donors as those who wish to receive a direct benefit from an elected official or as citizens who just want to express their affinity for a candidate through a donation. We argue that family members who donate to candidates follow a more expressive affinity compared to private donors, and donation patterns over time should differ for both types of donors. We track donors across several elections and using a close election regression discontinuity design in a sample of Colombian municipalities, we find that donating to the winner of the mayoral race significantly reduces the probability of donating in the next election. Consistent with our theory, such an effect is larger for family members than for private donors. Moreover, unlike family member donors, private donors are more likely to receive public contracts when donating to an election winner and more likely to donate in the next election after receiving a public contract. This paper points at evidence that both expressive and benefit-oriented donors coexist and actually have different behaviour across time.