He was a Progressive Conservative member in the Legislative Assembly of Ontario from 1975 to 1990, and was a cabinet minister in the governments of Bill Davis and Frank Miller.
He worked as a sod and potato farmer and executive and owned a real estate company in Alliston.
[5] McCague served as parliamentary assistant to the Treasurer just before the 1977 election, and was brought into Bill Davis's cabinet on September 21, 1977, as Minister of Government Services.
McCague tried to convince Davis to remain in office for another election, but afterwards endorsed Frank Miller to succeed him as party leader.
McCague was narrowly re-elected in the 1987 election, defeating Liberal candidate Gary Johnson by only 306 votes in the redistributed constituency of Simcoe West.