A political party can be defined as ‘any group, however loosely organised, seeking to elect governmental officeholders under a given label’ (Epstein 1979: 9). Building on Key’s (1964: 164) fundamental distinction and Katz’s and Mair’s (2002: 113) modifications, this chapter describes and analyses the interaction of German voters and party elites at three distinct levels: the ‘party-in-the-electorate’, the ‘party-in-the-government’ (Key) or ‘party in public office’ (as Katz and Mair put it), and the party organisation outside the legislature, particularly the ‘party on the ground’ (Katz and Mair 2002). Our analysis focuses on individual parties and also covers the party system as ‘the system of interactions resulting from inter-party competition’ (Sartori 1976: 44, emphasis in the original). We will aim to track important continuities in, and changes to, voting behaviour in respect of the main German parties individually and of the party system as a whole, concentrating on the period since unification in 1990. Drawing on a number of theoretical perspectives, including theories of electoral change, theories of organisational reform in political parties (in response to electoral change), and coalition politics at the governmental level, we will develop our argument as follows: after introducing the main parties and analysing continuities and change in voting behaviour and party membership, we will analyse how political parties have responded to the growing levels of political uncertainty in organisational terms and will seek to address the seemingly paradoxical question why Germany’s party system has remained relatively stable at the governmental level (the party in public office), while parties in the electorate and parties as organisations have become far more fluid and vulnerable. (On the electoral system in Germany, including proportional representation and the statutory minimum of 5 per cent of the national vote a party should achieve to be represented in the Bundestag, see Chapter 6.)

Six parties were represented in the German parliament or Bundestag between the first election after unification and the general election of 2013. They are the main ‘actors’ on the stage of the Bundestag. We will briefly characterise the main parties and their challengers, starting with the parties of the centre-right and right (for some further short portraits and further information see Hornsteiner and Saalfeld 2014).