Very rarely does anyone assume the leadership of a major political party without having gained experience as an elected representative at some level of government.
Brian Mulroney pulled it off. True, at the end of his term he was the most hated prime minister in memory and the federal Progressive Conservative party was decimated in the 1993 election. But he did manage to win two consecutive majority governments; an unheard of feat for a party without the word “Liberal” in its name.