Complex sentence: She led the Quebec wing of the party, the Parti social démocratique du Québec, from 1951 to 1957 through three provincial elections using her position as a platform to campaign against the government of Maurice Duplessis.
Split into simpler sentences: She led the Quebec wing of the party, the Parti social démocratique du Québec, from 1951 to 1957. She also used her position as a platform to campaign against the government of Maurice Duplessis.