Between 1943 and 1985, the party built up a political apparatus that became known as the Big Blue Machine. During much of this time the party was very centrist, ofting running to the left of the Ontario Liberal Party. This reached its hieght under Bill Davis, a "Red" (i.e. more liberal) Tory who was premier of the province between 1971 and 1985.
The Conservatives were reduced to a minority government in 1985 and were finally defeated in 1987 by David Peterson of the Liberals.
In 1995, Mike Harris led the party to an election victory, running on a "Common Sense Revolution" platform. He won a second majority in 1999. Harris resigned in 2002 and former finance minister Ernie Eves became premier. On October 2, 2003, the PC Party was defeated in a general election by the Liberal's lead by Dalton McGuinty.
Recent PC policies have included lower taxes, increased privatization of services and a reduction of provincial debt. The party has been criticized on issues such as health care, the environment and education.