Check out the Democracy Now debate between Kshama Sawant, Socialist city councilmember in Seattle and member of Socialist Alternative, who is a Sanders supporter and says she will not support Clinton, and Mike McGinn, former mayor of Seattle from 2010 to 2013. This link has a video and transcript of the debate.
McGinn keeps using the Democratic establishment canard that said establishment can be tempered by the Bernie movement, keeping it in check. One thing this election has highlighted is that the establishment in both parties does not give one shit about the ordinary people in their base. And both lie to their faces about their agenda and what’s going on. Clinton’s rhetoric has had to be more progressive in order to win votes. But does anyone honestly believe her? Her trustworthiness numbers say no we do not. Is she better than Trump? Maybe not. See this Ning IPS thread on a progressive third party.