Dominant Parties

Parties are considered dominant if they achieve electoral dominance both vertically and horizontally. Vertical electoral dominance is achieved when a party surpasses a threshold of vote or seat shares. In the literature, the demarcation of this threshold varies from a majority of at least 40% to 70% of raw votes or lower-house seats. Horizontal electoral dominance requires such a majority to be sustained longitudinallyusually over a generation. For example, Italy's Christian Democratic Party, an archetypal dominant party, controlled the parliamentary executive for 36 years (19451981).