I'm not saying they are the same Big Tents.
They are firmly different voters with different priorities in each
What I mean is that the Republicans can fit Anti-Vaxxers, Racists, Transphobes, Gun Nuts, etc... who care about different things while not concerning themselves in what they differ on.
The left spends more time arguing about the minutia of what they don't agree with... which results in less time focused on the macro they agree on.