The Supreme Court confirmation process for Brett Kavanaugh didn’t fully break the nation, but it did prompt more Americans to wonder if that moment is approaching. It’s been a while in coming. Over the past year, I’ve heard thousands of my Nebraska constituents and dozens of my colleagues in the Senate, of both parties, say roughly the same thing: “It feels like we’re at a tipping point, and X or Y might be the final, make-or-break battle.”

More Republicans and Democrats are placing politics at the center of their lives. Both...