Catalan politics also influences Spanish politics as a whole due to the presence of Catalan nationalist parties in the Spanish Parliament, whose political support is often required by any given winner of the Spanish general elections to form majorities. Convergence and Union has been described as being "long the region's dominant political party". Catalan politics is also noted, to a lesser extent, for the influence exerted by the Socialists' Party of Catalonia on its sister major party, the Spanish Socialist Workers' Party (PSOE).