Leave the party and go where??? The Communist Party USA??? They certainly ain’t going conservative and join the conservative party. Oh, wait, they can join the RINO party and be apart of the republican establishment party. That should work for them.
Green Party. Jill Stein has been courting them heavily, to the point of offering Sanders that party’s Presidential nomination (with Stein as VP). She’s been at the DNC, outside, rallying Sanders supporters.
Communist Party USA stopped running presidential candidates in about 1987, choosing to work through the Democrats. No joke.