"Progressives should not make the same mistake that Ernst Thälmann made in 1932. The leader of the German Communist Party, Thälmann saw mainstream liberals as his enemies, and so the center and left never joined forces against the Nazis. Thälmann famously said that ‘some Nazi trees must not be allowed to overshadow a forest’ of social democrats, whom he sneeringly called ‘social fascists.’
After Adolf Hitler gained power in 1933, Thälmann was arrested. He was shot on Hitler’s orders in Buchenwald concentration camp in 1944."
The moment it makes waves on even a local level, one or both major parties would begin to invest resources in crushing it wherever it appeared.