The difference between the extreme wings is miniscule. Methods, Objectives and Goals are the same, just the arguments differ slightly.
In Germany half of the voters of the Ultra-Left Party "Linkspartei" went within one election to the Ultra-Right Party "Alternative für Deutschland". Even starnger, the AfD is financed by Putin who wants to recreate Stalinism, which is Ultra-Leftist, while the AfD wants to recreate a Führer-Cult which is Ultra-Right. And still both cooperate perfectly.
But don't think the US is better. While Linkspartei and AfD together are 15% in the US the equally Extremist-Trumpists are close to 50%.
People need to understand that the Extremists on the wings are closer to each other than to the middle. While the middle tries to better things in small steps the Extremists want to burn the house down with everyone inside and then see who survives.