With a POD of 1900 or later, make democracy be percieved as obsolete and archaic, much like many people view monarchy nowadays.
If we see Fascist Italy remain neutral in World War 2 and lead a Fascist Bloc during the Cold War, you might see a surge in Fascism throughout the world which sees it gradually succeed the Western Democracies and becomes a model for quite a few countries to implement.This was basically the case in the interwar period, Mussolini compared fascism and democracy to electricity and gas lamps.
There was a pervasive sentiment that liberalism, in both a political and an economic sense, were 19th century anachronisms that were proven obsolete in the era of total war and command economies, or at least heavy-handed state intervention that maintained private property rights on paper.
It's largely forgotten nowadays but Nazi Germany was a model for authoritarians in eastern Europe before 1939. France appeared to be economically stagnant and in geopolitical decline, while Germany seemed to have recovered from the depression and begun surging ahead.
There's more than a grain of truth behind this. Fascist groups that were opposed to liberal democracy relied on implicitly democratic ideas to attack their opponents, they criticized the existing oligarchic parliamentary systems as corrupt and unresponsive to the people's concerns.When even the most totalitarian regimes find it advantageous to put "democratic" in their official titles, I think your OP is gonna be a pretty tall order. You'd probably need something on the scale of Nazis(not Stalinists, because even they paid lip service to democracy) winning World War II, grabbing up almost all the land in the world, and raising entire generations to believe that elite rule, identified as such, is a good thing. And even then, they'd eventually probably come around to calling themselves "democratic", if for no other reason than to have a leg to stand on when saying that the few remaining democracies really aren't.
There was a pervasive sentiment that liberalism, in both a political and an economic sense, were 19th century anachronisms that were proven obsolete in the era of total war and command economies, or at least heavy-handed state intervention that maintained private property rights on paper.
With a 1900 POD? Hard to kill off the ideology at that point, or at least in a way that it's seen as "obsolete" rather than just "anarchic and dangeriously radical". I suppose one way you might be able to pull it off would be a strong surge in popularity of and reasearch into the Eugenics movement, if its in a positive Eugenics (IE Breeding a race of "natural aristocrats") rather than negative Eugenics (IE Purging the negative aspects of the gene pool). If you can do that, producing a gene-perfected class (I have no idea if this is even possible or how it would be done) who's objectively so much smarter than everybody else that you get the population to admit their decisions are bound to produce better results, than maybe you could get a neo-Oligarchic idea to take hold if states run by the Humans 2.0 thrive while old democracies struggle economically.