‪David Moscrop‬: why the NDP vote is collapsing. To it, I'd add this: We're seeing Duverger's revenge. FPTP is doing what his law suggests: polarizing the electorate between two parties

I would say the reason the NDP, the Bloc, and the Green vote has been collapsing is that this is an election where the key ballot question is one of foreign policy, particularly to do with the US. The NDP, the Bloc, and the Greens are all primarily domestic policy parties, so they're not speaking to the ballot question. The Liberals have a leader who does speak to the ballot question, and so do the CPC in that he's largely aligned with the IDU and MAGA. So, it's a two-party race this time. Doesn't mean it will be that way next go around.