zizek talks about this a lot. who are trump's most loyal fans? sure, there are the harvard educated elitists who like that he lowers taxes on the rich and the business magnates and whatnot. but the bulk of it in terms of absolute numbers is the redneck poor people
why do they support trump? because their jobs were lost to outsourcing, their wages aren't going up so housing is more expensive, their towns are slowly rotting away. they see these things and feel a (in my opinion, justified) anger towards the establishment.
someone like Trump and the GOP in general comes around, blames the gays and immigrants and tells them they will fight for them. we all know it's a lie and that they are voting against their interests - but the MAGA propaganda has gotten to them first
these same triggers (stagnant wages, anger towards the establishment/elites, erosion of infrastructure, inaccessible healthcare) also causes people to become leftists
these people could have easily flipped one way or the other and the only different is propaganda. we need to reach out to these people and convince them that the left has viable solutions for their problems. if you're interested, i can find a zizek bit where he talks about this but I've seen it myself talking to a lot of trump-supporting conservatives.
some of them are racist bigots and whatnot, but others are just really ignorant old folk who genuinely want the best for most people and have been misled by propaganda