“…The direction of such adaptation was, moreover, towards concentrated and centripetal party structures in the EP, as national party delegations migrated from small to large parliamentary groups, and alignments of the centre left (PES) and the centre right (EPP) formed the core of most voting coalitions. The bias towards concentration of group membership and centrist voting were, in turn, linked to the institutional contexts of party politics in the EP; first, to minimum thresholds for the formation of groups (Corbett et al, 1995); second, to the rule that most parliamentary powers required a majority of the EP's membership and not just of those turning out to vote (Bardi, 1996;Hix and Lord, 1997); and, third, to the 'institutional design' of the EU as a 'legislative triumvirate' (Kreppel, 2000, p. 342) in which the probability of the EP achieving its objectives is constrained by the preferences of two other cross-party bodies: the Commission and Council of Ministers.…”