Start arming themselves for a long and bloody resistance against the GOP soft dictatorship which will be existent from the late 2020s to probably around 2040 at the latest. While not ideal, this is the best way they can reduce the time of the dictatorship in a long assymetric underground campaign. Seriously that is the future of what will remain of the left wing in America before either serious reforms or a complete collapse (bad for everyone) come the next economic crash.
I would say "preparing" rather than "arming".
I know the conservative obsession with ammosexuality has deeply warped this country, but random collections of citizens owning guns does not solve political problems, even ones that involve state abuse of force - for that you need a
militia (if you need arms at all). And there's a great deal that can and should be done that has nothing to do with arms at all; if Americans are fighting a second Civil War in our streets and fields, we've already lost many times over.
Random terrorism directed at an illegitimate government only gives it (undeserved) legitimacy and excuses for the actions it wants to take anyway, without accomplishing anything positive. Relentlessly criticizing it and refusing to comply with it while presenting a better alternative will be far less destructive and far more effective. (Current Democratic leadership are far too "bipartisan" - which really means "continuing comfort for the leaders of the status-quo" - to be effective leaders under such circumstances.)
