The unions have a very strong sway on the "grew up union Democrat" people.

Especially in a somewhat insulated state like WV where media and even the internet is not as big a part of people's lives but welfare is. They are somewhat protected from the daily Democrat insanity and even if they are aware of it maintain the 90's "blue dog" Democrat belief that there's still a wing of the party that represents Conservative, religious southern working class viewpoints in the face of the "northern fat cat" Republicans.

They aren't really aware that Manchin is the only one left of that mold. The rest of the party has gone full Marxist Revolution.