Dylan Matthews for Vox.

Sanders is the most vocal exponent of this critique currently, but he’s hardly the only one. At least since the progressive movement of the early 1900s, a prominent strain of American liberalism has identified the undue influence of moneyed interests, primarily through campaign donations and lobbying, as the fundamental problem in American politics, the one issue that needs to be fixed before the political system is capable of fixing anything else.

Sanders’s version is actually more plausible than the one others have articulated. He ties it to a broader call for working-class unity and revolution. More typical is the less comprehensive version Harvard law professor Lawrence Lessig expressed during hisshort-lived presidential bid, which holds that if Congress were to simply pass some good government reforms — in particular campaign finance reform — legislation that liberals have been pushing for generations would suddenly be possible, even easy, to pass.

Matthews has apologized to Lessig for this aspect of his column.