How much damage, exactly, did Bernie Sanders do in 2016? That question has become nearly untouchable, thanks to Sanders’ passionate boosters in the media, not to mention (RIP, my mentions) his dedicated social media fan base. Yet, as Sanders seemingly gears up for another presidential run in 2020 — including a new round of attacks on anyone seen to pose a threat to his coronation — the question of what his scorched-earth style of campaigning might cost the Democrats becomes newly relevant.

Before we even begin, we must admit that Sanders’ run has done lots of good, namely by mainstreaming socialist ideals and class consciousness. We need student debt forgiveness and free college, universal health care, a Green New Deal, and universal basic income, and I am grateful that the Sanders movement has directly or indirectly placed those things within the realm of possibility. But it is also true that by the time Sanders conceded his primary loss in August 2016, the Democratic primary had become a long, bitter civil war. Many Sanders supporters protested Clinton at the Democratic National Convention and continued to protest her well into the autumn of 2016. Others, the notorious #BernieOrBust contingent, threatened to switch their votes to Trump or stay home.

At the time, it was easy to write these people off. A dippy Susan Sarandon quote about how “Donald Trump will bring the revolution immediately” or an isolated bizarro blogger (pour one out for H.A. Goodman, bastion of socialism and/or Daily Caller contributor and/or self-styled “JEWISH TRUMP VOTER 2020”) may have provided some entertainment, but there was no proof that they were representative of any widespread problem.

Over the past year, however, data has trickled in about which forces propelled the Sanders campaign to its surprising primary success. While none of that data is damning in isolation, it does contradict the narrative pushed by Sanders’ loudest supporters: that his campaign was a nigh-unstoppable force for good, propelled by the people’s embrace of his populist ideals. You know this narrative. It comes attached to the argument that a Sanders candidacy is the silver bullet for defeating Trump in 2020 and concludes with the battle cry “Bernie would have won.”

Yet a 2017 study found that one in 10 Sanders voters — enough to swing the election — switched their support to Trump for the general. The deciding factor was not their opposition to capitalism (support for the TPP, for example, played virtually no role) but their racism; if a Sanders voter disagreed with the statement “white people have advantages,” they were more likely to vote Trump by the time November came around. There have also been multiple reports that the Sanders campaign was boosted by Russian troll farms, which evidently hoped (not without reason) that a troubled primary would damage Hillary against Trump.

What this data says is that many Sanders supporters were not voting for him but against Hillary Clinton.

Again: Bernie Sanders received some support from racists, but that does not make him racist. Bernie Sanders received some support from Russia, but that does not make him a Russian asset. It’s not uncommon for frustrated primary voters to switch allegiances. Hillary Clinton’s own 2008 dead-enders, the PUMAs, voted Republican in large numbers and often seemed motivated by racist hostility against Barack Obama. We also know that racism was a significant predictive factor for Trump support, meaning even if Sanders ran against Trump in the general election, that 10 percent may have voted Republican anyway. And, of course, there can be no doubt that the Russians favored Trump all along.

That’s the problem. What this data says is that many Sanders supporters were not voting for him but against Hillary Clinton — the candidate who, in 2016, was seen as the chosen successor to a black president and most openly courted black voters, the candidate who was targeted by Russia, and the only other candidate in a two-person race against Bernie Sanders. Few U.S. politicians have inspired as much visceral dislike as Hillary Clinton. You can debate the role of sexism — I have — but when your opponent has been hung in effigy and sold as a tear-apart doll, it’s fair to say she has enemies. Sanders was able to harness that. He could embody the anti-Clinton vote and gather support from anyone who disliked her simply because, for most of the primary race, he was the only other option.

All of this will be different in 2020. Sanders will not have the benefit of running against Clinton, and he will have to compete with multiple rivals. Maybe Sanders really has popularized his message and platform enough to win on his own merits. Maybe his popularity will fizzle out as he becomes just another face in a crowded primary field. But then, there is the third, most unpleasant scenario: Maybe Sanders will decide that his success depends on manufacturing another villain.

This brings us — with much dread and weariness — to Beto. Over the 2018 midterms, O’Rourke became the internet’s dreamy indie-rock boyfriend. He had a skateboard! He was in a band with Cedric from At the Drive-In! O’Rourke also received record campaign donations, nearly defeated Ted Cruz in a deep-red state, and, after his defeat, took a meeting with Barack Obama. The buzz O’Rourke created and the places his support came from — media, social media, young people — was reminiscent of Obama. It was also reminiscent of Bernie Sanders. Which probably explains why, shortly after news of the Obama meeting broke, high-profile Sanders supporters began denouncing Beto O’Rourke in the press. Most infamously, David Sirota misleadingly framed a screenshot about O’Rourke’s campaign contributions (0.62 percent of which came from individual workers in the oil and gas industry) to imply he was in the pocket of Big Oil.

There is no acknowledgment, after 2016, of just how dangerous that attitude might be or of what other forces might be arrayed against the candidates in question.

I never caught Betomania, but it’s hard to ignore the larger, more obvious pattern — that this has happened to every candidate who has gathered enough buzz to pose a challenge to Sanders, deserving or not. I can believe that O’Rourke is a sizzle in search of a steak. But I find it harder to believe that O’Rourke is the face of Big Oil, and Elizabeth Warren embraces neoliberal capitalism at its most rapacious, and Kamala Harris is the carceral state incarnate, and Cory Booker is popular only due to racial tokenism, and Kirsten Gillibrand is in deep with Big Tobacco, and Amy Klobuchar, I don’t know, never brings a hot dish. They haven’t gotten to her yet.

The problem is not the reporting on these politicians’ individual sins, some of which is correct, and some of which, like Sirota’s freakout, is wildly exaggerated. It’s not even the “boy who cried wolf” quality of hearing so many similar denunciations in a row, though it is increasingly tough to take any one hit piece seriously. It’s the implication that these errors are unilaterally disqualifying and should outweigh any good the candidates might do. There is no acknowledgment, after 2016, of just how dangerous that attitude might be or of what other forces might be arrayed against the candidates in question. The decision to tie Gillibrand to the fact that she represented tobacco companies as a young lawyer, for example, took place before she called for Al Franken’s resignation and her candidacy was nuked from orbit by powerful donors. Sanders’ core supporters went for Gillibrand as hard as possible, right out of the gate, not realizing that institutional sexism would eventually do their work for them. Again.

The lingering anger many Clinton supporters feel at Sanders isn’t because he ran against her or because he ran with the goal of pushing her to the left. Again, many of the ideas Sanders has nudged into the American mainstream are good ones. That mistrust stems from how reckless Sanders was with the anger he riled up. Long after he knew he’d lost, he continued to call Clinton “unqualified” or insist she was the head of a massive conspiracy. He knew it could do no good, and he should have seen that the dangerous toll of his negative messaging — the death threats to Democratic Party officials and reporters, the demolished coalitions and names dragged through the mud, the ever-increasing threat that if there was no Bernie, the nation itself would bust — was rising. Yet he appeared shocked that he could not undo the damage; even Bernie Sanders got booed for not supporting Bernie Sanders.

To destroy one rival this way may be regarded as a misfortune. To destroy them all looks like carelessness. It looks like a candidate who has not yet learned to push his advantage in any other way than going negative, even though any of his rivals, should they defeat Sanders, will be the only protection we have against a second Trump term. To be clear: If Sanders is the nominee, I will vote for him. The good he might do outweighs the harm. It’s just not clear that Sanders knows how to say that about anyone else. The viciousness of the 2016 campaign may just have been a mistake, even if it was a bad one. If the pattern continues into 2020, we will have to call it something much worse.