Building on these two literatures, I propose a model that allows deriving expectations on the direction of a party response as well as conditions for party responsiveness. Doing so, I try to reconcile the diverging positional logic presented in the previous section (Pontusson and Rueda, 2010; Idema, 2009). The argument is essentially dynamic as it develops expectations about positional movements by political parties between elections.
As a start, I argue that parties have two goals that push them into opposite directions and which they need to balance (Aldrich, 1995). Several assumptions are necessary for the argument. Policy competition takes place on one dimension along which the distribution of voters is single-peaked. Parties have core voters who are to the left or the right of the centre of the distribution of all voters2. Following the median/swing voter logic, parties have an incentive to expand their voter base and appeal to swing voters in the centre. At the same time, however, parties also have incentives to send signals to their core voters to ensure they turn out at the ballot box. The first motive, therefore, drags parties to the centre of the policy space while the latter one pushes them towards the fringes of the policy space. I suggest that parties essentially try to deliver to both groups but under different contextual circumstances (such as an external shock), targeting one group becomes more important than targeting the other. When an external shock hits and core voters benefit disproportionately, parties have some margin to moderate their positions away from their core voters and move to the centre
2Adams and Somer-Topcu (2009) empirically show that left-right voter distributions in 15 European
countries are approximately single-peaked. I assume that core voters have clearer ideological pref- erences thus appear to the left or right of the centre of the policy space (see e.g. Ura and Ellis (2012, p.282) for the US case). Swing voters, in contrast, can theoretically be to either side of a political party in a multiparty context. Adams and Somer-Topcu, however, make the point that most non-centrist parties can expect electoral gains from moderating their positions (2009, p. 680; Ezrow, 2005). From this argument and based on the cited literature, it follows that the assumption that swing or more easily swayed voters are in the centre of the policy space is reasonable, also in a multiparty context.
of the policy space. If their core voters suffer disproportionately, parties have a strong incentive to send signals of reassurance to their core voters by polarising their position and move away from the centre. Both moves are contingent on parties’ expectation about their core voters’ turnout and voting behaviour after an external shock. I argue that core voters in a good economic position are more likely to still turn out while under distress, they might credibly threaten to not cast their vote or vote for an alternative party.
On top of these positional dynamics, I propose that this behaviour is not necessarily symmetric for parties of all ideologies. In principle, this behaviour should only be observed for parties with clear links to core voter groups. If a relevant core constituency is hit by an external shock, the representing party should be responsive. If parties lack this electoral connection to certain voter groups, the model’s prediction is less clear and competing parties should either be less responsive or not respond to the external shock at all in their positioning. Given that voter groups often differ by ideological preferences, the party response should be moderated by party ideology. Depending on the party ideology, we should then see an asymmetric partisanship effect where some parties, those with the electoral connection to a core voter group, respond disproportionately strong to an external shock while others do not or at least show more ambiguous positional responses. The asymmetry can also result from different expectations about the turnout of core voter groups. If these expectations are not equal between parties, a party that always needs to target its core voters to ensure their mobilisation does not have the margin to moderate its position and should not display the hypothesised behaviour. As a result, some parties might be able to use their discretion while others do not3.
The argument applies in principle to a variety of external shocks. The main condi- tions which need to be met are a clear electoral connection between a relevant voter group and a party as well as a salient external shock that disproportionately improves or hurts the voter group’s economic well-being. Researchers are left with the task to identify contextual factors where we can observe the hypothesised behaviour. As a first evaluation of the argument, I move on to introduce one of several testable implications of the outlined theory: housing market fluctuations.
3Most of the cited models are based on two-party systems. In such a setting, a shift by one party always
affects the other party as it opens or decreases space for the competitor and a strictly asymmetric
effect is hardly possible. In a multiparty setting, however, it is possible that only some of the
competing parties respond to an external shock as party competition is more complex. For instance, the incentives to move to the centre of the policy space are less clear. Swing voters, however, do not necessarily have to be in the centre of the policy space but parties still face incentives to target voters outside traditional core constituencies to expand their voter base. In such a case, swing voters are characterised as ideologically close, but not entirely predisposed voters that parties attempt to persuade at low costs. Targeting voters outside the core constituency also critically depends on the existence of competition for similar voters. For instance, a party located to the very right of the policy space might have more leeway to moderate and move to the left without losing voters than a party that still faces competition from the right. In the empirical analysis, I take some steps to control for these different forms of party competition.