Mr. Trump also recognized that the principal reason for this disconnection is that the party’s penchant for tax-cutting has devolved from a policy preference into a sacred cult, unconnected to reality or anything resembling fiscal conservatism. Revenue-draining cuts inevitably starve the public services that the aging and economically insecure white working class increasingly depends on. Popular support for the teachers’ strikes in Arizona, Kentucky, Oklahoma and West Virginia in recent weeks indicates that even solidly Republican states are turning against this kind of anti-government economic doctrine.

The example of Kansas shows that Republicans are capable of curbing the radicalism in their ranks. Gov. Sam Brownback’s “real live experiment” in reckless tax cuts led to economic stagnation; a collapse in state revenues; and hugely unpopular cutbacks in public services that damaged not just schools but also hospitals, highways, law enforcement agencies, programs for the disabled and children in foster care. In 2016, moderate Republicans replaced dozens of Mr. Brownback’s conservative allies in the Kansas Legislature and, a year later, voted to restore state revenues over his veto.

Mr. Ryan, who served as Mr. Brownback’s legislative director when Mr. Brownback was a senator, was the Republican Party’s most prominent cheerleader for the Ayn Rand-inspired idea that society’s “makers” should be lavished with tax cuts while its “takers” should be deprived of a social safety net. The downfall of Ryanism, and the rise of Trumpism, indicates that the decades-long domination of the Republican Party by ideological conservatism is finally giving way to an outlook that, for good or ill, better reflects the party’s changed base.

The white working class clearly wants to protect and build upon the public sector, not destroy it. In a comprehensive recent study of voter attitudes, Larry Bartels, a political scientist at Vanderbilt, found that Republican voters are still inflamed by cultural issues but are nowhere near as hostile to government as most political analysts imagine. A majority of Republicans support government action to ensure access to quality health care and provide a decent standard of living for people unable to work. A substantial minority favors reducing income differences and helping families pay for child care and college. The anti-government agenda pushed by Republican megadonors like the Koch brothers simply doesn’t resonate with rank-and-file party voters.

It’s no secret that the interests of the party’s donor class have been sharply at odds with those of its base. But political parties ultimately have to deliver concrete benefits to their core constituents if they want to retain their support. And politicians have to respond to the needs and hopes of their voters, not just pander to their fears and hatreds.