In recent high-profile speeches, Joe Biden has been performing a high-wire rhetorical act. He is not shying away from the f-word (fascism) – the ultimate condemnation in humanity’s political vocabulary – even if he qualifies that condemnation by calling some on the American right “semi-fascists”.

At the same time, he is putting a lot of effort into separating “extremist Maga Republicans” from the decent folks on the right, be it your nextdoor conservative neighbor or Biden’s old chums across the aisle in the US Senate. No matter the level of polarization, the president appears to suggest, you can have a barbecue with the former, and with some senators you might still be able to have a beer and discover a shared humanity (unless it’s Mitch McConnell).

On the face of it, this seemingly contradictory rhetoric makes sense as a political tactic; less obviously, it’s also the right thing to do in a democracy where you ought to be careful about throwing blanket accusations at large parts of the citizenry. But, absent a plan for how to address Trump’s “base” and bring it back into the democratic fold or, failing that, render it politically powerless, this approach is likely to contribute little to securing the American experiment in self-government.

Biden evidently wants to find a way politically to isolate what he calls extremists. But there’s a problem with the very term here: “extremism” points back to the exhausted and counterproductive political language of centrism. Centrism isn’t a bad thing as such (I realize some readers of this column will disagree), but it turns toxic in a situation of asymmetrical polarization: the centrist, in order to avoid the charge of extremism herself, studiously has to aim for some equidistance. But the political battlefield can then be reshaped by those willing to adopt ever more outlandish positions and thereby shift the center itself. Evidently, no matter what he does or says, Biden (and even the most pro-corporate Democrats in Congress) will have the charge of “radical left” hurled at them by Republican leaders.

The image of center and extreme also makes it easier for Republicans to push back against Biden as “divisive” – because centrism’s kitschy political fantasy is ultimately always bipartisanship of the reasonable huddling together in the middle. Anything that creates conflict and increases political passion – no matter how justified – might then be framed as detracting from the project of “bringing us all together”. In any case, the point of democracy is actually not to bring us all together; rather, it is about allowing us to deal with our conflicts in a peaceful manner. To be sure, those engaged in conflict should ideally see themselves as partners in the same project of self-government; that’s why it is crucial not to declare one’s opponents to be enemies or traitors, and that’s why Biden is also right not to suggest that every single person who’s ever voted Republican ought to be ostracized.

Trump and other right-wing authoritarian populists generalize about – and incite hatred against – citizens they claim do not truly belong to the polity; just remember the former president’s tendency to respond to critics not with arguments (as anyone in government justifying their policies would) but by declaring the critic simply un-American. Biden and others are wise in not wanting to react in symmetrical fashion.

But getting the rhetoric at least somewhat right does not solve the underlying political challenge. For years, Never Trumpers have made a lot of noise, a lot of great ads, and, according to critics, also a lot of money; but they have never articulated a strategy for how the remaining supposed mainstream Republicans can either disown, or, as some would like to see it, harshly discipline the Maga base.

This summer’s primaries will have convinced many on the right yet again that they do not necessarily have to debase themselves like Kevin McCarthy and kiss the boss’s ring – but that they must never, ever criticize the boss openly. As long as Republicans assume that they need truly Trumpists to win, they can at best aim for the kind of dissimulation which Glenn Youngkin demonstrated in Virginia: run as a responsible corporate type, but also make sure that citizens who have committed to the Trump cult turn out. As the cliche goes, they have to be fed “red meat”, and no matter how rotten the meat (such as lies about the teaching of race in schools), someone has to be willing to serve it.

The notion that one can control this process – let’s give something to the base, but govern as a pro-business party otherwise – has been seen as crucial to a post-Trump American right. But it’s based on the very fantasy that finally imploded with Trump’s rise in 2015: that it’s OK to have some racist dog-whistling, some crazy culture war rhetoric, as long as it’s supervised by Republican leaders and strategists who can dial it up or down as they see fit. By now the lesson should be obvious that, if you keep offering red meat, at some point you can’t control the diet anymore.

Instead of insulating some Republican leaders from criticism, Biden should have made it clear that Trumpism is also their responsibility and that it’s their job to deal with “extremism” – even if they have to pay a political price. If they’re signaling that they’re not willing to pay that price, at least they’ve revealed how little democracy is ultimately really worth for them.

• Jan-Werner Mueller teaches at Princeton and is a Guardian US columnist. His most recent book is Democracy Rules