Donald Trump is the most politically extreme president the United States has seen since Andrew Jackson — and possibly in its entire history.

That claim requires both precision and evidence, because “extreme” is a word that loses its analytical force when applied indiscriminately. So let us be precise about what it means and what it does not.

Extreme, as used here, is simply a relative term: it describes significant departures from the institutional norms and constitutive conditions — judicial independence, electoral legitimacy, civil service neutrality, the peaceful transfer of power — without which liberal democracy cannot sustain itself across time. But it carries no ideological valence in itself.

It is worth distinguishing extremism from its frequent neighbor: radicalism. For two centuries radicalism has been the struggle to complete the deepest promises of the Enlightenment — humanist, universalist, and stubbornly unfinished. In United States history, radical programs are those directed toward completing or extending the promises American liberal democracy has made to itself (even when they have been made propagandistically or in self-delusion) — in the Declaration of Independence, in the Fourteenth and Fifteenth Amendments, in the democratic architecture the republic has explicitly constructed over time. In this sense, Franklin Roosevelt was radical. He dramatically expanded the federal government into areas of American life it had never touched, restructured the relationship between citizen and state, and did so against the sustained opposition of concentrated wealth and entrenched institutional resistance.

But it is Lyndon Johnson by whom I have measured every president since. He signed the Civil Rights Act knowing, and saying openly, that he was surrendering the South to the Republican Party for a generation — and did it anyway. He delivered a commencement address at Howard University in 1965 articulating a theory of substantive equality that was well to the left of mainstream liberal opinion and remains contested to this day. And he stood before a joint session of Congress in March of that year, at the height of the Selma crisis, and closed with the words of the movement itself — We shall overcome — in an act of presidential rhetoric so unexpected, so electrically charged with moral commitment, that it has no equal in the history of American presidents since Abraham Lincoln.

Both men paid enormous political costs. Both broke things in the process. None of this is to say that either presidency was unblemished — Roosevelt’s internment of Japanese Americans was an act of liberal democratic failure, not extension, but what they were breaking toward is what matters: a more complete conformity between America’s most difficult and thrilling covenantal claims and American practice, a forcible widening of the circle of those to whom liberal democracy’s promises actually applied. That is not extremism. That is the republic’s most demanding, enduring, and frequently enervating impulse.

Trump’s departures from norm are of a categorically different kind. In his second term alone, impounding congressionally appropriated funds in defiance of congressional authority, issuing executive orders challenging the Fourteenth Amendment’s birthright citizenship guarantee by executive fiat, defying judicial orders, and the unprecedentedly explicit and public use of raw federal power against named political opponents. Add to that the dismantling of the merit-based civil service through Schedule F — potentially the most structurally consequential transformation of the executive branch in over a century. His rhetoric has been correspondingly without precedent: the press designated “enemy of the people,” an explicit public oath of retribution against political enemies, open admiration for authoritarian leaders abroad, and the sustained refusal to accept the legitimacy of a lost election, culminating in January 6th, 2021 — the first violent rupture of the peaceful transfer of power in the republic’s history.

None of this can be characterized as completing any commitment latent in America’s founding documents or creedal claims. What is being broken are not barriers to democratic inclusion. What is being broken are the constitutive conditions of democratic life itself.

The only president who invites serious comparison is Andrew Jackson — and the comparison illuminates rather than diminishes the claim. Jackson defied the Supreme Court, dismantled the central bank against elite consensus, expelled Native Americans through policies brutal by the standards of his own contemporaries, and constructed a theory of presidential authority grounded in personal mandate rather than institutional constraint. His democracy was plebiscitary rather than liberal: the leader’s will, confirmed by the mob, supersedes the constraints of courts, legislatures, and law. Trump’s is the same theory, more fully elaborated and more aggressively prosecuted against a constitutional order two centuries older and more elaborately constructed than the one Jackson faced. Whether Trump therefore exceeds Jackson is a question this argument leaves deliberately open — the incompleteness of the constitutional architecture in 1830 makes the comparison genuinely difficult to resolve. What is not open is the category: these two presidencies represent the same species of political extremism, and no other American president belongs in that company.

That species has a defining characteristic: both Jackson and Trump constructed their political identity around a narrowed definition of who constitutes the legitimate political community, and used executive power to enforce that narrowing against institutional resistance. Roosevelt and Johnson were extreme relative to the political consensus of their times — but they were extreme in the direction of a more complete liberal democracy. Jackson and Trump were extreme in the direction of a less complete one, and in their assault on the institutional conditions that make democratic self-correction possible at all.

What is at stake in Trump’s presidency is not a policy agenda that can be reversed by the next election. It is the machinery by which reversals remain possible. That is what narrowing destroys.