Private funding of U.S. federal elections is at record levels, with most money contributed by a few very wealthy individuals and organizations. Cross-partisan majorities of the American public consistently express concern, and proposed campaign finance reforms are introduced as frequently in Congress recently as earlier in time. Despite these facts, and that successful twentieth century reforms often were preceded by corruption scandal, that these continue today, that there remain political entrepreneurs for reform, that reformers continue to use corruption framing, and that the Supreme Court’s 2010 Citizens United decision left some reform strategies open, no proposed campaign finance reforms to curb moneyed interests’ influence have been enacted since the 2002 BCRA. We address this puzzle through comparative process tracing of forty reform efforts receiving consideration in a congressional committee from 1907 to 2024. We identify three ideal-type reform trajectories—scandal as agenda-setter, the Supreme Court as agenda-setter, and a multiple legislative trajectories type—through which campaign finance reforms through 2002 sometimes were successful. We then show how and why a combination of changes in the political, media, and legal environments doomed reform efforts post-2002 and especially post-2010 to almost certain failure. We draw implications for federal political discourse and policy-making more generally.