Donald Trump has lost the presidency, but the 2020 election has confirmed the extraordinary mobilising power of his movement. He still won close to half of an unusually high turnout. Republicans are likely to keep their majority in the Senate (depending on the outcome of a runoff in Georgia in January) and cut back the Democratic majority in the House of Representatives.

It’s worth remembering that the power of Trumpism was vastly underestimated before 2016. That election revealed a new bloc of voters who, though ostensibly conservative in the mould of the Republican Party under Ronald Reagan, were largely untroubled by their candidate’s affront to conservative values. The Trump presidency sometimes looked like an escalating stress test for these voters. How much did they really care about patriotism, morality, honesty, sexual fidelity, financial probity and, ultimately, competence?

“Not much” seemed to be the clear answer. The polls showed Trump’s base as rock solid. His popularity has moved within a tiny bandwidth, shown by charting his approval/disapproval ratings across his presidency. Viewed over four years it looks like a straight line when compared to his predecessors.

So it is surprising how little is still really known about Trump voters. As this election has shown, America’s enormous polling industry still can’t accurately measure them, having by and large predicted a Joe Biden landslide. And academic researchers are still catching up. In the words of one excellent review of Trumpian politics, “since the extremity of the moment is making familiar categories seem toothless, many researchers are now showing a creative flair for improvisation.”

The most important unknown about Trumpism now is whether it really is a cohesive and enduring bloc, or whether it was actually a temporary coalition held together one man’s personality and electoral success?

Radical groups tend to splinter, especially when they fail. Republican leaders’ limited support for Trump’s determined refusal to concede may the first signs of facture.

If Trumpism can live without Trump then it could be even more powerful. It seems plausible that a Republican leader who was more competent and personally conservative could turn it into a far more powerful force. Not just for winning elections but for governing. Benjamin Wittes was one of the first to realise that Trump’s chaotic and impulsive style would weaken his hard-line agenda, shrewdly characterising the administration as “malevolence tempered incompetence”. A more competent Trumpist could achieve much more.

But it’s far from clear that Trumpism will live on as a unified bloc. Radical groups tend to splinter, especially when they fail. Republican leaders’ limited support for Trump’s determined refusal to concede may the first signs of facture. Trump TV could accelerate that trend. And there is some evidence that Trumpism was always a coalition of divergent interests. In a 2017 study Emily Etkins found at least five types of 2016 Trump voters. Researchers have found it easier to identify the differences between these subgroups – on ideological and economic issues – than their commonalities.

Trump supporters may be united by a preference for authoritarianism (although what that means remains unclear). But they may equally be united by Donald Trump’s particular and unusual personality, especially what they see as his “authenticity”. If so, Trump’s impulsive and chaotic style is probably essential ingredient of this authenticity. A second perceptive observation from Wittes is that despite Trump’s continual lying, “he’s actually incapable of being dishonest about his own emotional state. He’s completely emotionally transparent.” That could explain why Trump’s popularity stayed so steady.

If that’s true it would be especially hard for any of the 2024 hopefuls – Mike Pence, Mike Pompeo, Nikki Haley or Tom Cotton – to fill his shoes, let alone build a more powerful movement. And even if Donald Trump Jr could more convincingly impersonate his father, it would be hard to see him also running a more politically-effective movement.

Joe Biden has pledged to be a “President who seeks not to divide, but to unify.” As the first President since Nixon to start his term without a Senate majority, he will need to reach across the aisle. He will struggle to find any common ground with a Republican party still beholden to Trumpism. But if Biden can find ways to divide his opponents, he may find it easier to advance at least some parts of his agenda.