i want to wheel myself back, though, and point out that there's a difference between trying to mobilize in the context of bourgeois politics (where you have to pay attention to things like demographic majorities in geographic riding boundaries) and trying to mobilize in the context of revolutionary politics (where these borders don't meaningfully exist). and, that is itself a difference between how a union operates and how a social movement works.
so, the march to birmingham, for example, attracted people from everywhere - it didn't matter where you were from, it mattered only that you were there. then, when everybody went home, they elected some more racists in these districts. so, where the movement was able to make a difference at a higher level of government, it utterly failed to enact meaningful change at a local level.
so, you have to ask yourself what you're doing, too. if you're trying to take control of the house of representatives, you're going to need union support, and you're going to need to adjust to their privilege, kind of whether you like it or not. but, if you're trying to act independently of the existing system and enact actual revolutionary change outside of it, you have to come face to face with the realities of how class exists inside of labour politics in the twenty-first century.