Just start another party
The far left has nothing in common with the moderates.
fukk the two party system..but if they are going to be so institutionally biased against third parties the only way to really change shyt is to take one over, break it down and either have dems jump ship and be their true selves, or do the same shyt they praise republicans for...fall in line behind the core principals that get carved out by progressives that can actually counter the trash Trump and republicans run on.
Once you do that...and have positions in office, THEN you can make a third party or at least throw your support behind one that gets founded from a position of power rather than 'outsiders' throwing rocks at tanks. Imagine a sitting president founding/legitimizing a third party, especially if corporate dems/republicans both fight against the will of the people and keep shyt from getting done.