Binyamin Appelbaum has a new and excellent piece on this topic:
Even the 2012 presidential election, which recorded $2.6 billion in campaign spending, underperformed many forecasts. And spending has declined in each of the last two congressional elections. Candidates and other interested parties spent $3.7 billion on this year’s midterms, down from an inflation-adjusted total of $3.8 billion in 2012, which was less than the $4 billion spent in2010, according to the nonprofit Center for Responsive Politics. (These figures do not include a few hundred million dollars in unreported spending on issue ads.) In fact, spending has dropped as the economy has grown and despite a series of contests in which at least one house of Congress was plausibly at stake. “Dire warnings rang out that the decision would herald a new era in politics,” wrote Adam Bonica, a Stanford University political scientist, in a 2013 paper about the effects of Citizens United. “Three years on, there is little evidence that these predictions have come to pass.” Over the past year, Americans spent more on almonds than on selecting their representatives in Congress.
The article is here, interesting throughout. Campaign finance, of course, is one of the areas where “the Left” is most likely to take an anti-science stance.