Last time i checked union dues couldn't be used on political contributions P.A.C. funds which are voluntary are used for that .
I'm told my union dues can't be used for direct political contributions. However, what about indirect contributions? You raise everyone's unions due to fund a union hall. The union then rents the hall and that money gets put into a separate account. Can that type of money then be donated to political parties? That is the question I always have.