This is Tommy Douglas. He was the premier of Saskatchewan, when his party, the CCF, became the first socialist government in North America. The CCF eventually became the NDP.
Check those trousers. Can you imagine a politician these days making such a bold sartorial choice? It seems like everything is so test grouped that politicians lose their personal quirks.
This is actually a very conservative choice, or at least was at the time. This is semi-formal day wear - a stroller, specifically. Black double-breasted jacket and gray striped or patterned pants is the more casual version of formal clothing for the day. It’s what a banker or lawyer would have worn in much of the English-speaking world in the early part of the 20th century. It’s still worn in most of the former British Empire for weddings during the day.
The last US President to wear some version of formal day clothing was Ronald Reagan.