Abstract The paper aims to contribute to the ongoing debate on the transformation and mainstreaming of new, particularly anti-establishment, parties as they enter the system and assume governmental positions. To demonstrate how participation in government can foster the mainstreaming of a formerly challenger (protest) party, this study examines how the Czech Pirate Party and its representatives have altered the framing of their communication. Using the case of intra-party debates around one of its most visible members, Jana Michailidu, we show how the framing of such issues can lead to attempts to mainstream the party in specific areas. A closer look at the case of the successful Czech Pirate Party seeks to explain whether the mainstreaming of a challenger party can strengthen its long-term survival and consolidate its position within the party system. In this context, we argue that understanding the dynamics of (European) party politics requires close attention to political competition that underlies electoral choices. Our research therefore focuses primarily on the supply side of political competition, particularly the content of parties’ political communication.
Naxera et al. (Sun,) studied this question.