[dude with glasses in a communist t-shirt, arguing] I'm the only leftist here, your opinions are TRASH
[dude holding a theory book on smug, arguing] Read theory you losers, you're all WRONG
[dude in an anarchist hoodie, arguing] Nuh-uh, I'm the only leftist here, you're SHITLIBS
[the three dudes are now caught in a cartoon fight, glasses gone flying, punches everywhere, while a firing squad of nazis are targeting them with rifles]
[a confused nazi asks] Why… why are they still arguing?
Taps sign again...
This isn't infighting between liberals and leftists, this is infighting between different flavours of leftism, like anarchism and marxist-leninism.
Or Marxism and Marxist-leninist.
Say what you will about Democrats. Outside of the elected ones. Most of them don't have a strong ideology. Just actually wanting things to improve. But I'm sure of how to go about it. And when you approach them like that. Are plenty likely to be sympathetic and allies.