@Setanta,
Set,
Check
Open Secrets list of top donors from 1989-2010...of the top twenty biggest donors in federal politics, 14 give predominately to Dems, 4 split their donations about equally and only 2 (#18 and #20) give predominately to the Repubs. Eleven of these top 20 are unions (all of which give 89% or more of their contributions to the democratic party.
The amounts of money the unions give dems is staggering...and is undoubtedly the reason that the Dems are so worried about Wisconsin. The same web site, if you add up the amounts given since 1989 just by the unions in the top 20 is $332M of which $321M went to Dems. By contrast the two repub leaning organizations in the top 20 gave away a total of $51M with $33M going to Repubs. Note the ten-fold difference between TOTAL dollars given by repub favoring organizations and that given to Dems by the unions ALONE.
I'm constantly amazed of this myth that Big Money is somehow a Republican strong suit...a quick perusal of this list puts the lie to that myth. In fact if you consider the $2.2B of corporate and special interest spending documented on that web site, 40% goes to Dems, 37% is about equally split and only 24% goes predominately to Repubs. Even adding up the actual dollars for each party doesn't support the myth....60% of the $2.2B went to Dems and 40% to Repubs.
Clearly unions are buying political influence and in far, far greater amounts than any business or capital-based organization.