In 1871, he was instrumental in creating the short-lived Parti National. Mercier successfully ran as a Liberal candidate in the 1872 election. He became Member of the House of Commons for the district of Rouville. He did not run for re-election in the 1874 election. In the 1878 election, Mercier was candidate in the district of St. Hyacinthe. He was defeated by the Louis Tellier, his Conservative opponent.
He became the leader of the PLQ in 1883. A practising lawyer, from 1885 to 1887 he was President of the Bar of Montreal. He strongly opposed the execution of Louis Riel in 1885; this event helped him win popular support, and the Quebec Conservative Party lost support because its federal counterparts had ordered Riel's execution. Seizing the opportunity to build a coalition with dissident Conservatives, Mercier revived the "Parti National" name for the 1886 Quebec provincial election, and won a majority of seats. However, the coalition consisted of mostly Liberals and only a few Conservatives, so the "Liberal" name was soon reinstituted. The Conservatives, reduced to a minority in the Legislative Assembly, clung to power for a few more months, but Mercier became Premier of Quebec in 1887.
Premier of Quebec
Seeing provincial autonomy as the political expression of Quebec nationalism, he collaborated with Ontario Premier Oliver Mowat to roll back federal centralism. Mercier initiated the idea of interprovincial conferences in 1887. He was the first Quebec premier to defend the principle of provincial autonomy within the confederation, campaigning to abolish the federal government's claimed right to veto provincial legislation. With his strong nationalist stance, Mercier was very much a precursor of later nationalist premiers in future decades who confronted the federal government and tried to win more power for Quebec. He promoted contacts with francophones in other parts of North America outside of Quebec including Western Canada and New England. Those francophones had not yet been assimilated into the English-Canadian or American culture to the extent they would be in the future. Mercier promoted reform, economic development, Catholicism, and the French language. He won popularity but also made enemies. He was returned to the legislature as the Member for the district of Bonaventure and his party won the 1890 election with an increased majority.
Political downfall
On December 16, 1891, he was dismissed by Lieutenant Governor Auguste-Réal Angers after a report concluded that his government had diverted public funds. He lost the 1892 election, and gave up the party leadership to Félix-Gabriel Marchand. He was brought to trial later that year and found not guilty when a second report concluded differently on the matter. However, his health had greatly deteriorated and his political career was over. He died in 1894 at the age of 54, and was interred in the Notre Dame des Neiges Cemetery in Montreal, Quebec.
Legacy
The following landmarks were named to honour Honoré Mercier:
Honoré Mercier Boulevard, located in the Quebec city centre.
Family
His son Honoré Mercier fils was a multi-term member of the Legislative Assembly of Quebec and a Cabinet Minister; his grandson Honoré Mercier III served one term in the Legislative Assembly. Mercier was Lomer Gouin's father-in-law and is a great-great-grandfather of NDP retired leader Thomas Mulcair.
Mercier, Honoré. "Answer of the Hon. Honoré Mercier to the Pamphlet of the Equal Rights Association Against the Majority of the Inhabitants of the Province of Quebec''
