RUTHFULLY YOURS

The First Step Act, which Mr. Trump signed last month, reduces the three-strikes penalty for drug felonies and retroactively limits the sentencing disparities for crack cocaine that disproportionately burdened African-Americans. That will reduce prison terms for about 2,000 current federal inmates.

Contrary to the depiction of Mr. Trump as racist, the act is wholly consistent with the way he campaigned in 2016. He invited minorities to vote for him because Democrats had left them behind: “What have you got to lose?” His pride in lower minority unemployment is obviously heartfelt.

In his economic policies too, Mr. Trump was anything but a flint-eyed conservative. He made it clear he wasn’t about to gut the welfare system. He wanted trade deals that would generally benefit Americans, and a border wall to preserve American jobs. In all this, he’s occupied the sweet spot in American politics, combining social conservatism with middle-of-the-road economic policies.

The media hasn’t paid much attention. Instead, it’s fixated on Steve Bannon and right-wing populism. Mr. Bannon makes common cause with European rightists and the brutish Yellow Vest protesters who destroyed a portion of François Rude’s “La Marseillaise” at Paris’s Arc de Triomphe. The Bannonites seem to have forgotten Edmund Burke’s lesson that while the English and Americans do revolutions well, the same can’t be said of the French.

U.S. conservatives aren’t like the European right, and there’s a reason. Constitutional liberties are the center of American nationhood and identity. If Americans (including Mr. Trump) have sometimes been illiberal, in time that’s been seen as un-American. The French National Front, Hungarian Prime Minister Viktor Orban—all that poses Molière’s question: What the devil have we to do with that mess?

If Mr. Trump’s tweets have been illiberal, so are the left’s policies. The identity politics that judges people by the color of their skin, the speech codes that silence conservatives on campus, the punishments meted out to religious believers who follow their convictions, the group rights that trample on individual rights—these are the causes that define today’s progressives. They’re antithetical to American liberalism.

Similarly, the left’s abandonment of the American Dream, of the idea that your children will have it better than you did, is a betrayal of liberalism’s noblest promise. If the left were serious about social and economic mobility, it would have to abandon its closest allies. Instead it will stick with the teachers unions and oppose school choice; it will support a broken immigration system that imports economic immobility; it will oppose any effort to relieve the regulatory burden that keeps so many progressives employed.

Imagine trying to explain any of this to a 1960s Democrat. Those liberals were patriots who loved America and would have had no use for people who see only its misdeeds. They stood up for what was right and had an exhilarating confidence in American justice and greatness. They knew the country had problems, but also knew we could solve them. Their passing left a hole in American politics, and whether Mr. Trump is re-elected will depend on whether he can fill that vacuum.

Abandoned by the left, rejected by the Bannonite right, mocked by Catholic integralists who seem unaware of its religious provenance, America’s traditional liberalism is the country’s political creed and the winning ticket in nearly every election. Trump’s challenge is to affirm unambiguously that noble tradition.

Mr. Buckley teaches at Scalia Law School and is author of “The Republican Workers Party: How the Trump Victory Drove Everyone Crazy, and Why It Was Just What We Needed.”