Commentary
There is only one answer to this question: Public sector unions. Anyone who argues otherwise is either misinformed or has a personal or professional motivation to delude themselves and others.
Before offering evidence of the financial power of public sector unions, consider the power these unions wield that is not explicitly financial. These unions operate the machinery of government, with everything that implies.
Public sector union members staff the countless local, regional, and state bureaucracies that businesses depend on to obtain building permits and business permits. Among the functions of these bureaucracies is the power to enforce regulations, review mandatory reports from businesses, and conduct inspections. It only takes a few union zealots within these bureaucracies to decide to target any business that contributes to a politician or a cause that the union opposes….