The importance of interest group ties in open-ballot proportional elections: effects of membership and endorsement on candidates electoral success

The process of representation is often not an ideal-type relationship between voters and their representatives. Interest groups play a major role in the entire political process and are often closely linked to parties and politicians. Whereas many scholars have investigated the importance of interest group linkages with political parties in the legislative process (see for example Otjes & Rasmussen 2015; Allern & Bale 2011; Eichenberger 2016) not much is still known on the effects of interest group linkages with candidates at the electoral level. Elections seem to have been generally ignored concerning the dimension of interest group-party and candidate interactions, although they constitute a crucial event in the democratic process. This article bridges this gap and provides a new perspective for interest-group-party interactions by focusing on the underlying question: how much and in which manner does interest group support, endorsement or membership matter for candidates' electoral success compared to other candidates in the same political party? We analyse data from a survey in the framework of the comparative candidate survey project (CCS) among more than 1'800 candidates from all seven major parties running in the Swiss national elections of 2015 as well as data from a Swiss elite database on interest groups (OBELIS). Switzerland is a unique case to study such relationship. In the open ballot PR system only candidate preference votes matter for electoral success and because of the Swiss militia parliament MPs remain closely linked to interest groups also once in office. Therefore close ties are of mutual interest: candidates get support in their campaign and interest groups get direct access to decision making should the candidate(s) they support be elected. In the framework of this project we collected information on all ties between individual candidates and various interest groups. This new and unique data set allows us to explore the nature of the ties and the varying importance of specific interest groups for candidates from different parties. More specifically it also allows us to understand the type of contributions of interest groups to candidates' campaigns, such as endorsement, campaign contributions, organisational and financial support. The expected results of this analysis are several, and not all of them are intuitive. Both the quantity and the quality of interest group ties are expected to be positively correlated with the probability of attracting larger shares of preference votes for the candidate that maintains such ties. The effect is expected to vary greatly between different party families and different interest groups and also depend on the nature of this link. This kind of approach should allow us to provide a geographically limited although deep insight on the nature of such ties in the electoral arena in a country where both the government and political parties are seen as relatively weak compared to the influence of interest group in decision making processes.