I completely forgot to add maybe the biggest driver of their Republican support. Religion. The poor in Mexico have been extremely susceptible to religious, especially Catholic and protestant, nuttery brainwashing for centuries. They pass that garbage down to their children, but recently many in the 50 and under generations who have strived to become educated have realized the stupidity of it all. That said, the majority still remain brainwashed and still believe Republican garbage is somehow "more Christian". Sheer delusion.
As much as I love the culture and enjoy visiting with her family I've had to make sure my 19 and 17 yr old daughters understand their grandma and grandpa, as well as other family members, are ignorant of truth and reality. But it was born out of poverty and no access to proper scientific education and that brainwashing is something very difficult to overcome. That's been a challenge for the last decade for sure.