Joseph Stiglitz pushed a story (How Trump Happened) that implies that the bad economy is the main driver of the Trump success in the republican primaries.
First I have in the past said that Trump is what many conservatives wanted all along and I still believe that is a big factor but I also think there is something else, which follows.
(Now I like President Obama as a person but, I think he has badly mishandled issues of race. He seems to me to be more decent that most politicians.)
When President Obama was elected many people hoped that he would defend the Government and whites to his black constituency but starting in the Travon Martin case and then in the Fergison case he seemed to side with the aggrieved blacks, before the evidence came in. He never pointed out that is was impossible to know if the Martin or Brown where the aggressors. He also failed to promise to blacks that he would attempt to rectify the situation from within if did turn out to be persecution of blacks so that they need not protest.
He also failed to point out that there are 340 million people in the USA 40 million of them are black and these things are bound to happen regularly, but that that does not mean whites are out to persecute blacks. It makes it worse that he has been great at understanding and presenting the statistics on Terrorism for example Obama
frequently reminds his staff that terrorism takes far fewer lives in
America than handguns, car accidents, and falls in bathtubs do. The same is true for whites and police killing blacks, they are relatively rare events. He could be shouting that from the house tops but no.
He failed to say "Look many whites voted for me, they are not so bad", and that if I can get to be president prejudice, while it still exists, is not holding blacks back significantly. That blacks can do well in the USA and most are.
Maybe wrongfully, but when people elect a minority they expect him put great effort in to reconcile his minority with the majority, Obama failed badly with this challenge, angering people and so Trump.
I fear Hillary Clinton will do the same always siding with women against men. For example the pay differential disappears when you factor in hours, occupations and career interruptions but she keep pushing the issue.