The party managed to elect a plurality of the city councillors in 1954 and in 1960 and its candidate Jean Drapeau became Mayor. However the majority of the City Council was made up of Independents and often blocked legislation proposed by the League.
Nonetheless, the League introduced party politics in Montreal's city government and abolished council seats reserved for businesses, city associations and agencies.
Drapeau lost his bid for re-elected in 1957. In the subsequent years, the party was plagued by conflicts between Drapeau and former Executive Committee Chairman Pierre DesMarais. In September 1960, 17 out of League's 33 councillors, led by Jean Drapeau, left and created the Civic Party of Montreal. By October 1960, the League was wiped off the political map.