Warner ran for the House of Commons of Canada as a candidate of the federal New Democratic Party in the elections of the 1972 and 1974, but finished a distant third in the riding of York—Scarborough on both occasions.
[4] The Progressive Conservatives under Bill Davis held a minority government throughout this period, and Warner served as a member of the opposition.
He was defeated by Progressive Conservative candidate Alan Robinson in the 1981 election, when the Davis government won a majority victory.
[5] Warner was re-elected in the 1985 provincial election, defeating Robinson by 219 votes as the Tories were reduced to a precarious minority government under the new leadership of Frank Miller.
[6] The Liberals under David Peterson were able to form a minority government with outside support from the NDP, and Warner served as his party's critic for Education and Skills Development over the next two years.