For decades, but particularly since the Citizens United decision, megadonors and lobbyists for special interests have exercised far too much influence within U.S. politics. Megadonors fund those who are the most likely to do legislative favors for the businesses and industries that are the sources of their wealth.
Sadly, America is on the verge of being a full-fledged plutocratic oligarchy: just look at the widening wealth gaps. The middle class, which was the guiding force in our democratic republic, no longer has much political influence.
Massive amounts of money are spent on American political campaigns.