@fu
The media is starting to put out a few articles questioning the two party system. That has never happened before. Democrats, just as much as Republicans, shut down efforts to bring in other partirs/voices. Both Democrats and Republicans are comfortable in the two party system, where they hold all the power.
Historically, Democrats attack progressive voices, who are part of their own party, far more than they attack Republicans. Democrats have also stopped progressive Democrats from unseating incumbent democrats, even when those Blue Dog Dems (centrist democrats with GOP agendas) block every good bill from passing in the house/senate.
Americans also call Republicans GOP, which stands for “grand old party.”