The model assumes that an opportunistic incumbent elected in the first period chooses the effort level in order to maximize reelection chances for the subsequent period. In the second period however, only altruistic incumbents will put in effort to help the needy because there is no incentive anymore for opportunistic incumbents to put in effort since a third period and therefore also reelection chances are nonexistent. As vulnerable citizens do not vote for selfish incumbents, they only vote for an incumbent in case they learned about effort put in by this incumbent in the prior period.
The above outlined model gives the following predictions: An opportunistic incumbent increases his effort level if voters have better access to media because in this case the population learns about the effort. Moreover incumbents show more effort if turnout is higher in elections, if a larger fraction of the population is