Various writers have developed models dealing with the problems facing a political party about to choose its election platform. 1 This Note shows, by means of a simple model, the importance that parties ought, in making this choice, to assign to a particular class of voters. This class consists of a subgroup of the usual ‘floating voters’ (i.e. those who change their vote from election to election). The subgroup consists of those among the floating voters whose votes may be influenced by their satisfaction or dissatisfaction with the programs the parties adopt. Such voters may be designated ‘swing voters’. Whether or not such voters exist it is not the purpose of this Note to argue. Certainly political parties - in the importance they attach to their election manifestos and to the promises they contain - behave as though they believe they exist.