> >but shows that most of the higher rate of turnout of unionists is
> >due to socioeconomic factors that differentiate union members from
> >others. With respect to voting preferences, union members are more
> >likely to vote for a Democrat for the House or Presidency than
> >demographically comparable nonunion voters, largely because union
> >members have attitudes and voting inclinations favorable to the
> >Democrats and to liberalism prior to a given campaign. Finally, the
> >study identifies a sizable group of nonunion persons with pro-union
> >attitudes that unions could potentially influence to maintain the
> >union impact on elections even with declines in union density.
If I read it correctly, this means that union membership is an intervening (if not spurious) variable i.e. political preferences make people more likely to be union members, and that also affects their voting behavior. If my interpretation is correct, this is essentially a "cherry picking" argument i.e. union membership is merely an identifier of a subset of the population with certain inclinations rather than the cause of these inclinations. This means that if union membership is expanded, it cease to identify the subset with pro-Democratic preferences, and the original relationship would cease to hold.
I think that the US society is on average quire reactionary due to a number of socio-demographic factors ranging from geographic /cultural/ethnic fragmentation, to religiosity, to institutional arrangements and to intensive pro-business propaganda - and it will take much more than expanding union membership to change these reactionary inclinations.
Wojtek