. . .So what’s going on? We have a theory, and it relates to that most famous of Supreme Court campaign finance cases, Citizens United, decided in 2010. When people talk about Citizens United – which allowed unlimited “independent” spending in elections and indirectly led to now infamous super PACs – they often talk about how it has opened the floodgates to massive amounts of money in our politics. This is a misconception. In fact, while the amount of money spent in federal elections since Citizens United has increased, the increase has not been particularly dramatic.

What has been dramatic is the change in who funds elections. Increasingly our elections are financed by just a handful of donors who make multimillion dollar contributions to support candidates for federal office. In 2010, the top 100 individual donors contributed just of $73 million to federal candidates, parties, and other committees, including super PACs. In 2012, that number increased to $380 million, and by 2016, it reached over $900 million.

All of this means that a few donors matter much more than they used to, and those donors can make threats that genuinely terrify members of Congress. Whereas before Citizens United donors of $100,000 or more could make up as little as 5 percent of all individual contributions in federal elections, after Citizens United they could represent as much as one in four dollars. That’s power!

The very real threat for members of Congress is that if they don’t get tax reform done, they may face heavily financed challengers in primary races. Vice President Mike Pence’s chief of staff made clear he understood the power of such threats when he told donors they should reconsider their contributions in the event the tax bill fails. “f I were you, I would not only stop donating, I would form a coalition of all the other major donors, and just say two things. We’re definitely not giving to you, No. 1. And No. 2, if you don’t have this done by Dec. 31, we’re going out, we’re recruiting opponents, we’re maxing out to their campaigns, and we’re funding super PACs to defeat all of you.” . . .