He ran for the House of Commons of Canada in the 1979 federal election as a candidate of the Liberal Party of Canada, but lost to Progressive Conservative John Reimer by about 7,000 votes in the riding of Kitchener.
[3] During his time in the legislature, Cooke served as a backbench supporter of David Peterson's government.
David Cooke was appointed Chair of the Select Committee on Free trade when the Peterson government came into being in the Summer of 1985.
When the FTA was finally signed, Cooke became the first chair of the first Standing Committee on Economic Affairs in Ontario.
The Liberals were defeated by the New Democratic Party in the 1990 provincial election, and Cooke lost his seat to NDP candidate Will Ferguson by 6,019 votes.