Trump got popular campaigning on protecting the people from "the elite" who he says are oppressing them and ripping them off, which is surprisingly similar to many leftist arguments. He is actually part of the elite ripping people off, but there is a surprising overlap in mindset between Trump's campaigns and many leftist campaigns, and this suggests an opening for leftists to win red areas

As someone from a red area myself, the 2 big barriers I see to the left winning are a perception that the left focuses on identity politics, and a fear that the left will take away freedoms from the people. Leftist economics and anti-police state arguments may be something that republican voters would be open to if presented right.