At the head of the revived Parti national, Mercier was the first Québec leader to win large popular support; by keeping alive the feelings aroused by Riel's hanging, he and his party won the election held late in 1886 after the Conservatives failed to cling to power and he took office as premier 29 January 1887.
À la tête du Parti national ravivé, Mercier est le premier chef québécois qui jouit d'un vaste soutien populaire. En attisant le ressentiment provoqué par la pendaison de Riel, lui et son parti gagnent les élections tenues à la fin de 1886, les conservateurs n'arrivant pas à se maintenir au pouvoir.