Winter began his political career in 1873 and entered Sir William Whiteway's cabinet as solicitor general in 1882. In 1885 Winter, then grand master of the Orange Order, resigned, expecting to become leader of a new Protestant party. He was disappointed but became a dominant influence as attorney general in Sir Robert Thornburn's 1885-89 administration.
Defeated in 1889, Winter became a Supreme Court judge in 1893. He resigned from the bench to lead the Tory Party to victory in the 1897 election. His administration soon ran into severe problems and was defeated in 1900. In 1909 Winter helped present Newfoundland's case in the North Atlantic fisheries dispute to The Hague tribunal.