I'm not canadian, but my understanding is that this is beyond just the tariff. It is in addition of the general attitude and (lack of) diplomacy from the US government towards Canada for the past few weeks.
White House Press Secretary said the quiet part loud when she announced that Canada can stop this tariff business by agreeing to become the 51st state.
Which would most likely lead to blue Congress and Executive, which is why they will first play shenanigans to ensure no more elections like we have known them.