A politician is supposed to represent others, the electorate, and not act selfishly. We know everyone will act selfishly in one way or the other, we are not angels. But there may be some ways to choose politicians that are more selfless than others. One interesting category of politicians in this respect are women.
It has been know for a long time that mothers and more generous to others than fathers. This is, for example, the reason why in many countries child benefits are paid to the mother. Also, women are more risk averse, as research reviewed by Catherine Eckel and Philip Grossman shows. Also, John Lott and Lawrence Kenny show that women's suffrage in the US has coincided with more liberal policies.
A particularly interesting experiment is the requirement in India that half (correction: one third) of village council seats be reserved for women (on top of slot for various castes), and half of council heads be women. Raghabendra Chattopadhyay and Esther Duflo document that while council members follow the interests on their own gender (and caste), those headed by women tend to favor infrastructure improvements.
Why would women want to provide more public goods? Uri Gneezy, Kenneth Leonard and John List compare matrilineal and patriarchal societies, where they conducted the classic experiment designed by James Andreoni: experiment participants decide how much money to distribute between a private and a collective fund. In patriarchal societies, women share more than men. In matrilineal societies, the reverse happens. It appears thus the dominated gender is more generous.