Electoral Competition on the Regional Cleavage: A Regression Discontinuity Design Analyzing the Effect of the Presence of Regionalist Parties on the Electoral Strategy of Non-Regionalist Parties

From the 1960’s on, Western democracies underwent a transformation: the decline of the importance of the class cleavage and the rise of voter volatility facilitated the rise of new parties. Among these new parties are regionalist parties who position themselves on the regional cleavage by advocating territorial autonomy and by promoting a territorial identity. Since the 2000’s, a growing literature has dedicated itself to uncovering the role of these parties, mainly focusing on what explains their success and/or failure to establish themselves and how regionalist parties adapt to the electoral system. However, much less attention has been paid to the other side of the coin, namely how non-regionalist parties react to these rising competitors. The main goal of this paper is to address this lacuna by investigating how the strategies of non- regionalist parties on the regional cleavage are shaped by the electoral competition with regionalist parties. More specifically, this paper makes use of a regression discontinuity design (RDD) that allows to assess what is the effect of the emergence and electoral results of regionalist parties on the strategies employed by non-regionalist parties, regardless of other confounding factors. We use MARPOR-date to measure parties’ salience and position on the regional issue. We then perform the RDD, with the entry of a regionalist parties in parliament as the treatment, and the change in salience and position on the regional issue of non-regionalist parties as outcome variable. While this technique has already been used to examine competition with radical right parties, it has yet to be applied to this specific case. The contribution of this paper is therefore twofold. First, it adds to our understanding of party competition more broadly by focusing on an underexplored case, namely competition between regionalist and non- regionalist parties. Second, it allows to more thoroughly understand the potentially stabilizing role of non-regionalist parties in societies divided by a politically salient regional cleavage.