In every democracy, established political parties are challenged by other parties. Established parties react in various ways to other parties’ presence. A key hypothesis in the relevant literature is that established parties can decrease an other party’s electoral support by parroting it, i.e., adopting its core policy issue position. In this paper we argue, and demonstrate empirically, that this hypothesized effect mainly occurs in the event that a critical prerequisite is in place. Parroting a party decreases its support only if that party is ostracized at the same time. We classify a party as ostracized if its largest established competitor systematically rules out all political cooperation with it. Analyzing 296 election results of 28 West European parties (1944-2011), we find evidence for a parrot effect –however, concerning ostracized parties only. On several occasions established parties have substantially decreased an other party’s support by simultaneously parroting that party and ostracizing it.
