There has been speculation at various times, most recently at the 2011 Canadian election, of the NDP supplanting the Liberals as a major party, since social democratic parties become major parties in most Anglosphere countries (i.e. Britain, Australia, New Zealand). However, the Liberals would likely be too well-placed to supplant.
So, if one is to have a centre-left party rise to power in Canada, perhaps the relatively weaker Progressive Conservatives could be relegated to third-party status.
Here is my challenge: have either the CCF or NDP become a major party, while the PCs become a smaller party, with both taking place between the end of WWII and the 1980s. Given that the OTL dominance of either the Liberals or PCs was largely dictated by regional swing and identity politics, this shouldn't be impossible.
Good luck
So, if one is to have a centre-left party rise to power in Canada, perhaps the relatively weaker Progressive Conservatives could be relegated to third-party status.
Here is my challenge: have either the CCF or NDP become a major party, while the PCs become a smaller party, with both taking place between the end of WWII and the 1980s. Given that the OTL dominance of either the Liberals or PCs was largely dictated by regional swing and identity politics, this shouldn't be impossible.
Good luck