Thomas Alexander Crerar

Thomas Alexander Crerar, the founder and first leader of the Progressive Party of Canada, had resigned the party leadership in 1922 and later sat as a United Farmers of Manitoba MP. As the Progressive movement dissolved in the late 1920s, Crerar formally joined the Liberal Party. Crerar had always been on the moderate, pro-Liberal wing of the Progressive movement — he had been a Unionist (pro-Borden) minister during World War I before launching the Progressives. His return to the Liberal orbit was seen as the natural conclusion of a political career that had always been closer to Laurier Liberalism than to the radical agrarianism of the Ginger Group.

Crerar became one of Mackenzie King's most important cabinet ministers, serving as Minister of Railways and Canals, Minister of Mines and Resources, and Minister of Immigration. He was later appointed to the Senate in 1945, where he served until his retirement in 1966 — at age 90, one of the oldest-serving senators in Canadian history. His journey from Progressive founder to Liberal cabinet minister illustrated the eventual absorption of moderate Prairie populism into the Liberal Party.