Cite as: 609 U. S. ____ (2026) 3 KAGAN, J., dissenting I A Soon after the 1972 presidential elections, Congress set out to strengthen the Federal Election Campaign Act in response to recent revelations of quid pro quo corruption. One apparent exchange of campaign contributions for a public-policy favor loomed especially large. As told by the Senate Watergate Committee, the deal involved price supports for milk, worth many millions of dollars to the Nation’s dairy industry. See Final Report of the Select Committee on Presidential Campaign Activities, S. Rep. No. 93– 981, pp. 623, 680 (1974). Originally, the Nixon administration had decided, after lengthy deliberation, not to increase the subsidies. See id., at 622, 633. But following a meeting with industry leaders, the President had a change of heart. He told his top aides to convey to the dairymen the “need to reaffirm their $2 million pledge” to his campaign “as a condition for the public announcement of [a milk subsidy] increase.” Id., at 648, 682; see also id., at 642–643 (describing the milk producers’ subsequent “middle-of-the-night rendezvous” to arrange for immediate “commitments of substantial financial contributions”). “The dairymen agreed, the announcement was made,” and “the promised contributions began to flow.” Id., at 682. When Congress resolved, a few years later, to amend the campaign finance laws, its “primary purpose” was to prevent such “quid pro quo corruption and its appearance.” McCutcheon v. Federal Election Comm’n, 572 U. S. 185, 197 (2014) (plurality opinion). The object was to shut down the “opportunities for abuse” associated with big campaign donations. Buckley v. Valeo, 424 U. S. 1, 27 (1976) (per curiam). At the heart of the 1974 reforms were so-called “base limits”—caps on the maximum amount any donor can give to a candidate’s campaign. The idea behind those limits is clear-cut. In a world where campaigning for office is expensive, candidates need financial contributions—and the