The Prime Minister of Canada is the primary minister of the Crown, chairman of the Cabinet, and thus head of government for Canada, charged with advising the Canadian monarch or federal viceroy on the exercise of the executive powers vested in them by the constitution. Not outlined in any constitutional document, the office exists only as per long-established convention (originating in Canada's former colonial power, the United Kingdom) that stipulates the monarch's representative, the governor general, must select as prime minister the person most likely to command the confidence of the elected House of Commons; this individual is typically the leader of the political party that holds the largest number of seats in that chamber. Canadian prime ministers are styled as The Right Honourable , a privilege maintained for life.