Blue collar workers, the foundation of the middle class in America, have long belonged, heart and soul, to the Democratic Party. I should know, I come from a solid blue collar family.
Growing up, my dad worked in the local mills. He spent decades, until his retirement, in one in particular, running heavy equipment and doing some of the most dangerous work in the world. He wasn't the only one in the family working in the mills or doing other blue collar jobs either. Grandparents, uncles, cousins all did the same. My wife's family is the same way.
These people worked hard (and still do) and many of them, when it came to politics, believed (and still do) that the only legitimate vote is one cast for a Democrat, regardless of what that Democrat's record or position on the issues might be. Why this attitude? Because as I've been told repeatedly by my own family members, "the Democrats are for the working people."