With his nativist and anti-immigrant policies and rhetoric, Trump is the rising tide that lifts all boats in the sea of right-wing extremism. When he stokes fears about caravans of migrants invading the United States, when he promotes anti-Semitic conspiracy theories about George Soros, when he allows that white supremacists are “very fine people,” when he repeatedly invokes the language of white nationalists and prioritizes their policy preferences, when he demonizes the press as the “enemy of the people,” when he spins conspiracies to obscure his own questionable activities, in all these ways and more he pours energy and coherence into a movement that might otherwise succumb to its well-established history of infighting.

Trump is holding the rickety structure of the alt-right together, for now, and probably for the foreseeable future. When he eventually leaves the public eye, the tottering edifice of the American far right might tip and fall. But for as long as he remains on the scene, it is likely to hold together. And the longer he and his fellow travelers remain in political power, the more likely it is that a more cohesive far-right movement will survive beyond his presidency.

The alt-right contains multitudes. It is a coalition of factions, but it is also an arena. Its social ecosystem, and particularly its online component, provide a venue in which ideas can compete, and adherents can flock to the ideological concepts that are most resonant and have staying power. As I have written previously, extremist movements are made up of discrete, identifiable elements, including a definition of identity, the description of a crisis affecting the extremists’ identity group, and a solution to the crisis that requires hostile action against an out-group. Within the alt-right, these elements are like a bag of Lego pieces; participants in the movement can grab the ideas they like and combine them to create highly personalized ideologies, tailored to their individual preferences.