Ignorance and hate from the people who voted for him. That's why he was elected (with abundant help from Russia). 
Trump's forte is putting the blame for White America's ills squarely on the shoulders of immigrants, Blacks, and any other person who doesn't look like the face White America sees in the mirror each morning. Because White America's ills CAN'T be their OWN FAULT, it HAS to be those OTHER PEOPLE! Trump is a master at assigning blame to others, when the REAL culprit is that face staring back in the mirror each morning.
Older, White Americans adore Trump, because he shares - and exacerbates - the hate and prejudices they hold dear. This is WHITE AMERICA, dammit! 
These people remember a day when the man of the house could go to the factory with his high school education, and earn enough to support a family of four or five. They had the house in the suburbs, the family station wagon, the summer trip to the beach, and the minorities KNEW THEIR PLACE, AND STAYED THERE! 
THESE ARE TRUMP'S PEOPLE! They've never adapted to the changing world, the global economy, the need for better education to keep up the rest of the world, and government "leaders" who were more than willing to sell them out, for the right price. And Trump LIES to them, saying ONLY HE can bring back those halcyon days of White America's short, failing memories.
It's difficult to defeat stupid. Stupid has a way of putting a stranglehold on people's ambition, fairness, and forward thinking. Until Democrats find a way to defeat stupid, these White Americans will continue to vote for people who will act COUNTER to their best interests, while blaming everyone else for THEIR shortcomings.
President Obama gave people HOPE, and hope CAN defeat stupid, BUT ONLY if those who HOPE also take some responsibility for their position in life, and are ready to ACT in order to change it. White America doesn't buy the "hope" thing, though. Not when they have a seemingly endless array of right-wing propaganda artists telling them it's NOT THEIR FAULT. It's those "OTHER PEOPLE" who are the problem! 
Stupid is a mighty, forceful foe. Stupid is a slowly sinking ship 
and few on that ship have the intelligence to figure out how to climb into the lifeboats that can save them. There are some other people in those boats who don't look like them, and they're scared to share a lifeboat with them. They'll choose drowning over working together to save themselves.
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