Earlier quoted context omitted.
The second US civil war only incidentally involves Trump. He happens to be the figurehead right now, but even if that changes we were on the brink before Trump and we will be on the brink after Trump. The underlying cause is a mistake of our founding fathers. Because of the winner-take-all structure of our elections, our political parties are forced to be forkophobic. The fact that we can't have a real Tea Party, to…
The states are free to choose their way of allocating their House representatives so long as they are directly elected. I don’t know if Proportional Allocation would count as directly elected, and to force all states to go along with it you definitely need an amendment.
Not necessarily — Congress has vast powers under the Fourteenth Amendment. See the just-published "Abolish the Senate" by lawyer and well-regarded liberal commentator Thomas Geohegan [0].
[0] https://thebaffler.com/salvos/abolish-the-senate-geoghegan