American politicians often rail against the undue influence of the rich. Bernie Sanders, a left-wing senator from Vermont, has decried a political system that allows billionaires to “elect the candidates of their choice”. On the campaign trail in 2016 Donald Trump claimed that the system is “rigged” in favour of big business. Elizabeth Warren, a senator from Massachusetts, kicked off her 2020 presidential campaign in February by swearing to combat a system that “props up the rich and the powerful and kicks dirt on everyone else”.

A new paper by Jeffrey Lax and Justin Phillips of Columbia University, and Adam Zelizer of the University of Chicago, suggests that the wealthy hold considerably less sway than is often assumed. Using data on 49 Senate votes on economic, social, and foreign-policy issues between 2001 and 2015, as well as on national survey data from polling firms such as Gallup and Pew, the authors analysed how often senators voted in line with the opinions of the rich and poor—defined as voters in the richest and poorest income quintiles in their state. They found that the rich get what they want from their senators about 60% of the time, whereas the poor receive their desired policy 55% of the time. When these two groups are on opposing sides of an issue, the rich get what they want 63% of the time. The middle class fare similarly when pitted against the rich.

That is unfair, yes, but not itself proof of a “rigged” game. For partisanship matters far more than the interests of affluent voters. According to the authors, when rich and poor voters oppose each other on a given issue, Democratic senators side with the rich 35% of the time and Republicans do so 86% of the time (see chart). Since legislators often follow the party line, it is little wonder that Congress is viewed as biased towards the rich when Republicans hold a majority. “Affluent influence that results from partisan influence may be worrisome,” the authors conclude, “but it is not the same as living in an oligarchy.”