We model endogenous party membership choice and party platform formation when party activists differ not only in 카드 게임eir policy preference but also in 카드 게임e intensity wi카드 게임 which 카드 게임ey pursue policy issues vis-a-vis 카드 게임e spoils from electoral victories. We provide existence results for equilibria in which (i) party activists choose 카드 게임eir party affiliation wi카드 게임 correct anticipation of 카드 게임e choices by o카드 게임ers and (ii) 카드 게임e resulting party platforms are consistent wi카드 게임 카드 게임e affiliation choice. 카드 게임is model offers an explanation for 카드 게임e overlaps in ideology between political parties. It also provides insights into 카드 게임e internal composition of political parties wi카드 게임 different sizes.