We observe that the Democratic Party in the USA is more likely to take actions that help poor people, while the Republicans like to help the rich. Yet a lot of poorer white folk vote Republican, so that the poorer states often have Republicans in power, amplifying the bad outcomes in those states. This is typically perceived as voter stupidity. This seems unlikely given 100s of thousands of years of human evolution favouring intelligence. We need to look deeper.
Humans have triumphed in the boom and bust cycles of the Earth's last few million years. What is likely to be a good strategy? When things are good we have lots of kids, and send some of them off to explore and settle. When things are bad the population has to shrink. What do our genes want us to do then? The higher status individuals are most likely to survive and reproduce. So the genes for low status individuals will like it (metaphorically) if it is closely related high status individuals who survive, as opposed to more distantly related individuals. So we should have an increased willingness for low status individuals to make sacrifices to promote the interests of high status individuals in their tribe against other tribes.
But how do we identify relatively more closely related individuals in large societies. In addition to the standard cultural identification (similar language, accent, facial expressions, attire, hair style), it is natural that people take notice of similar appearance.
The rich in America, at least the visible ones, seem to be mostly of European origins. So perhaps there is a reason for poor whites, feeling (mostly incorrectly) that things are going bad, to support the Republican party and its support for hereditary wealth. And perhaps it is instinctive for the high status individuals to promote tribalism. It's certainly working for them today, but as we saw in Europe in the 30s, it can easily get out of hand.
So it would be possible to attack Trump's support by identifying wealthy foreigners and those of non-European heritage who will profit by Trump's and wider Republican plans. Of course this contributes to inflaming social tensions, and should not be used unless there seems to be some chance of Trump winning. After the election we hope Democrats in Congress will move vigorously to address the decline of the middle class, most particularly by printing money and spending it on much needed infrastructure.