This study analysed contending views over interpretation of Islam in politics between two major Malaysian Islamist political parties; Parti Islam Se-Malaysia (PAS) and Parti Amanah Negara (AMANAH), and how the differing discourses taken were reflected electorally. It explored the historical dynamics of conservatism and progressivism within PAS, and by extension AMANAH as its splinter party. Primary and secondary documentation analysis was conducted on resources ranging from writings and speeches of respective party figures, official documents and extensive literatures written on the subject. The research concluded firstly, a preference over Malay communalistic ideas in PAS was the main factor that led to the systematic elimination of AMANAH. Secondly, while PAS has a long historical root centred upon creation of Islamic state, implementation of hudud, and exclusivist attitude towards others, AMANAH views Islam from the higher objectives of syariah that emphasizes good governance, justice, and inclusivity regardless of religious and ethnic differences. Thirdly, a mutual contestation existed, id est not only AMANAH challenged the conservative Islamist narrative of PAS, PAS also challenged the progressive Islamist narrative of AMANAH. Finally, electoral contestation between PAS and AMANAH shown that AMANAH managed to edge over PAS in 14th General Election (GE14). However, PAS capitalized on ethnic sentiments to gain unprecedented electoral success in 15th General Election (GE15). While this research was limited to existing data in the field, future studies could utilize quantitative methods to explore how electorates on the ground grasp respective parties’ ideas and contestation.