USAian here. IMHO, the bigger problem in US politics (I don't know about Canadian) is that the first-past-the-post electoral system by its nature polarizes the country. The system encourages it by penalizing anyone who votes for a moderate. Say that A and Z are the extreme candidates, and a moderate called J enters the race. J is closer to A in ideology, so will pull more voters away from A than away from Z. This splits the A vote and practically guarantees a win for Z, even if there's a sizeable majority who would have voted A if J wasn't an option. So, that's the first problem I see. We need an electoral system where you can vote for a moderate without fear of throwing the win to the candidate you like the least.
I'd go after political parties next. People here in both parties are actively demonizing the other. It's simply become cheering for your team. A lot of that is related to the problem above, but a lot is that we seem to like team sports. People are very loyal to "their" team. So, take away team membership. Demote political parties to the advisory level, no more or less powerful than any other group. Candidates wouldn't belong to a party, wouldn't have an (R) or (D) after their names. Instead, candidates would be endorsed by a party, just like candidates are currently endorsed by, say, the Teamsters or the NRA. The endorsement says "This candidate's goals currently align with ours." rather than "This candidate belongs to us." Just like the Teamsters and the NRA could (in theory) both endorse the same candidate, a middle-of-the-road candidate might actually get endorsed by both the Republicans and the Democrats. The aim here is to lessen the cheerleading section who think, "We want this guy to win because he's our guy!" without actually examining the candidate's actual positions or qualifications. I also want to stop the ridiculous "majority party is in charge" situation in Congress. That's just plain dumb. Remove the party identity, remove the disproportionate benefit of having a single person more in the majority party. Maybe congress will vote their consciences rather than voting strictly to score a win for their party or worse, voting simply to stop the other party from scoring a win.
It's probably hopelessly naive, but maybe it'll work for the next 250 years before it unravels like the current system has.