Unfortunately, and one of the primary reasons for the continued existence of unions, they don't do so in an effective or efficient manner. While contrary to popular belief, not every union sends large amounts into political coffers. Certainly not in comparison to corporate PACS.
The unions were responsible for almost half of Bronco's contributions in 2012. That's significant.
"The beauty of the Second Amendment is that you won't need it until they try to take it away."---Thomas Jefferson