The prime minister of Canada is the official who serves as the primary minister of the Crown, chair of the Cabinet, and thus head of government of Canada. Twenty-four people have served as prime minister. Officially, the prime minister is appointed by the governor general of Canada, but by constitutional convention, the prime minister must have the confidence of the elected House of Commons. Normally, this is the leader of the party caucus with the greatest number of seats in the house. However, in a minority parliament the leader of an opposition party may be asked to form a government if the incumbent government resigns and the governor general is persuaded that they have the confidence of the House.