Haidasz entered politics when he ran in the 1957 election, and became the Liberal Member of Parliament (MP) for the Toronto riding of Trinity.
He was defeated in the 1958 election in which John Diefenbaker led the Progressive Conservative Party to a landslide victory.
Haidasz returned to the House of Commons of Canada in the 1962 election, now representing the Toronto riding of Parkdale.
[1] Prime Minister Pierre Trudeau recommended his appointment to the Senate to Governor General Jules Léger.
During his career, Haidasz was instrumental in the passage of Medicare, the Canada Pension Plan and Income Supplement, the Clean Air Act and other legislation.