“…The multi-dimensional spatial conception of political competition dates back to Lipset and Rokkan (1967) and it has become standard practice in the US with the works on (roll call) voting behavior in Congress (McCarty et al, 2008;Poole, 2005;Poole and Rosenthal, 1997). Then, this practice has moved to Europe both at national level with the Comparative Manifesto Project (Gabel and Hix, 2002;Gabel and Huber, 2000;Budge, 2001;Klingemann, 2006) and at the EU level with the project Resolving Controversy in the EU (Thomson et al, 2006(Thomson et al, , 2012Thomson, 2011) and the study of the European Parliament's party system (Bakker et al, 2012;Hix et al, 2006). The literature on interest group influence should follow these steps (see also Bunea and Ibenskas, 2016).…”