Abstract: Political transformations since 1998 have implications to part’s ID. In the election, the parties are no longer elected cause of the weakening party affiliation. This study aims to analyze the factors caused the weakening of voters loyalty to the party. The method used is a qualitative research. Technique data collection through field observation, interview and focus group discussion. The results of the study addressed that the source of weakening voters loyalty are national, local, party’s internal, pragmatic factors: the national factor consisting of the rules of the establishment parties, the electoral system, the threshold of votes/seats. Local factors are decline in the support of NU and Muhammadiyah, the movement of popular cadres and party candidates. Party’s internal factors consist of the conflict parties, the performance of the party. Finally is rational economic behavior of the voters.