Most unions I suspect already have some form of within-union democracy. The small union I'm a member of works on a sort of federation basis, broken up by physic

Most unions I suspect already have some form of within-union democracy. The small union I'm a member of works on a sort of federation basis, broken up by physical location. So members of District 26 vote for a District 26 rep, who goes to a meeting of the union leadership and then votes there. In this way, representatives are not exclusively associated with job classifications (e.g., all the programmers vote for programmer reps, the accountants for accounting reps, etc.) but are instead only loosely associated with classification. So one rep mostly, but not exclusively, represents the accountants, but also might represent the secretary in the same office. I think it's an okay system, and I'm sure different intra-union democratic structures have been studied, but to an extent I think you have the same problems as with local elections: it's difficult to get people to be informed and care, absent some huge community-wide issue. What was the difference between Rep A and Rep B in the last election? Who knows?