The DNC is paid, controlled opposition. The only way they won't roll over is if there's a leftist Tea Party that forcibly takes over the DNC and outs all the corporatists.
I'd recommend creating a private room and inviting people to it instead. You can optionally enable encryption as well, but keep in mind it has perfect forward secrecy, so people won't be able to view messages from before they joined.
I'd recommend letting the next loaf rise for maybe double the time as this loaf. General rule is you want the shaped dough to expand to 3x its size before baking.
Matrix. Federated and self hostable, open source, supports encryption