Your claim that "the vast majority of poor white people in America" are Republican voters needs some serious proof before I would even consider giving your question any serious consideration of an answer. Do you have it?Since the vast majority of poor people in America are white and since the left seems to think this is an attack on poor people, and since the vast majority of poor white people in America appear to vote Republican, wouldn't this be the opposite of what you're suggesting?
I will even help you get started. Here are the official poverty level figures for the USA
Now take those and show me how the "vast majority" of white folks living in poverty are voting Republican. And this time I will be the one waiting for the evidence.