Several Political parties operate in Italy, and historically they have been even more than today. No one party has ever had the chance of gaining power alone and thus parties must work with each other to form coalition governments.
However, since the 2008 general election, only five major parties are represented in Parliament. On one side the centre-right People of Freedom and Lega Nord support Berlusconi IV Cabinet, on the other side there is the centre-left opposition composed of the Democratic Party, which includes in its parliamentary ranks the Italian Radicals, and Italy of Values. The Union of Christian and Centre Democrats is the only party outside the two big coalitions to be represented in Parliament, in a increasingly two-party system.
Other minor regional parties are represented in Parliament, notably the Movement for Autonomy, the South Tyrolean People's Party and the Valdotanian Union, while many other parties are active or represented at the regional level.
Christian Democrats led the government consecutively for 46 but five years. Between 1983 to 1991 they steadily shared government with Socialists, Republicans, Democratic Socialists and Liberal altogether. These were the years when several Northern regional parties demanding autonomy organized themselves at the regional level. In 1991 they federated themselves into Lega Nord, which surprisingly became the fourth largest party of the country in the 1992 general election.
In 1992-1994 the political system was shaken by a series of corruption scandals known collectively as Tangentopoli and the subsequent police investigation called Mani pulite. These events led all the major parties of government to disappear. Consequently the Communists, who had gathered themselves in the Democratic Party of the Left in 1991, and the post-fascists, who launched National Alliance, gained strength. Following the 1994 general election media tycoon Silvio Berlusconi became Prime Minister at the head of a coalition composed mainly of three parties: its brand new party called Forza Italia (joined by many members of the five parties of government), National Alliance and Lega Nord.
Between 1996 and 2008, Italian political parties were organized into two big coalitions, the centre-right Pole of Freedoms (which was re-named House of Freedoms after the re-entry of Lega Nord in 2000) and The Olive Tree (re-named The Union in 2005) on the centre-left. The centre-left governed from 1996 to 2001 and again between 2006 and 2008, while the House of Freedoms was in government between 2001 and 2006.
In 2008, The Union ceased to exist, because the new-born Democratic Party decided to break the alliance with the Communist Refoundation Party and the other parties of the coalition, except Italy of Values and the Italian Radicals. In the centre-right, the foundation of Forza Italia and National Alliance merged to form The People of Freedom, which continued the alliance with Lega Nord.