They just don't have any leadership. Trump is a bad leader, but at least he is recognizable. Who do the dems have? Bernie? Chuck and Nancy? No one has really stepped up to the plate yet. Someone will, but they are taking their sweet time.
The Democrats have no one on the horizon worth a damn, and the Party is no longer based in American thinking.
Your idea of American thinking is quite different than that of many Americans. One might even say "most" Americans who vote, given the popular vote in 2016.
And no issue put forth.