President Trump’s approach to governance is unlike that of his recent predecessors, but it is also not without antecedents. The groundwork for some of this dysfunction was laid in the decades before Trump’s emergence as a political figure. Nowhere is that more true than in the disappearance of the norms of American politics.

Norms are defined as “a standard or pattern, especially of social behavior, that is typical or expected of a group.” They are how a person is supposed to behave in a given social setting. We don’t fully appreciate the power of norms until they are violated on a regular basis. And the breaching of norms often produces a cascading effect: As one person breaks with tradition and expectation, behavior previously considered inappropriate is normalized and taken up by others. Donald Trump is the Normless President, and his ascendancy threatens to inspire a new wave of norm-breaking.

This would be bad enough if he were entirely a one-off, an amoral figure who suddenly burst onto the scene and took advantage of widespread discontent and an electoral system that tilts outcomes in the direction of his politics. But Trumpism has long been in gestation. His own party, sometimes consciously, sometimes not, has been undercutting the norms of American politics for decades. As the traditionalist conservative Rod Dreher has written, “Trump didn’t come from nowhere. George W. Bush, the Republican Party, and movement conservatism bulldozed the field for Trump without even knowing what they were doing.”

The United States has to hope that in the long run, more Republicans will join the ranks of the conservatives who already understand the damage Trump’s indifference to informal ethical benchmarks is inflicting on our political system. But to do so effectively, they will, as Dreher suggests, have to reexamine their own past and the deterioration in the standards of political behavior that took root in their party. And this will only happen if Republican officials come to see altering the course of the modern conservative movement as a political imperative.