There is a diminished middle because the Democratic Party has moved so far left as to espouse socialism and flirt with communism, holding up radical Leftists as folk heroes. The reaction by the Republican Party and the Conservative-leaning voters that make up the majority of the Independent block has been to solidify in opposition to the radicals that wish to turn America into a Soviet-style society.
The radicals who the state-run media claim are social heroes:
Patriotic Americans who the state-run media claim are dangerous, violent, racist radicals:
You do the math.