Some on the left were outraged at Sanders’ decision to un-endorse Uygur, or at those who were calling for it. They say that aiming to appease detractors is a futile task. It’s more important for a progressive presidential candidate and for progressive voters to support likeminded candidates down-ballot than to focus on past transgressions. A progressive White House saddled with an uncooperative Congress will accomplish little other than great legislative drafts, a handful of executive orders and a slew of unconfirmed judges. A president Sanders, they’d argue, needs a Congress with Uygur in it, warts and all.

All those points may be true. But they miss the bigger issue—and the reason that Sanders was, in the end, right to disavow his fierce supporter. The problem isn’t entirely with Cenk—it’s also with Bernie.

His diehards might not want to think about it this way, but Sanders himself has unique vulnerabilities that made endorsing Uygur a strategic error. It would have damaged both candidates’ chances of accomplishing their shared vision for America. Sanders’ prospects in 2020 are both too great and yet too fragile, in this ruthless news cycle, to risk attaching himself to someone whose past behavior threatens to reignite fires the Sanders campaign has worked so diligently to extinguish.

Sanders spent much of the run-up to 2016 refuting accusations from liberals that he was both a lesser feminist than Hillary Clinton and even actively a misogynist. Much of this criticism was preposterous, turning a willful blind eye to Sanders’ perfect voting record on pro-choice measures. There was the now-comical focus on his habit of finger-pointing during debates, and even the pretense that a satirical piece he wrote about a rape fantasy in the ’70s was serious. But there were also more serious allegations about how he had run his 2016 campaign—allegations regarding staffer diversity, pay parity between men and women, and the handling of sexual misconduct. Sanders has apologized for his former staffers’ negative experiences and committed to do better in 2020. This year, his campaign was the first in U.S. history to unionize. Still, when Elizabeth Warren announced her run this cycle, a new narrative emerged that Sanders might be sexist for even staying in the race, and his supporters sexist for supporting him over her—as if the two senators were interchangeable as candidates.

Then came Uygur the endorsement. Sanders campaign chairs Nina Turner and Rep. Ro Khanna had already endorsed Uygur to much less fanfare, but with Sanders’ own announcement, the reactions came rolling in: Jezebel asked “Why Did Bernie Endorse Extremely Gross Sexist Cenk Uygur”? The Advocate declared “Bernie Sanders Endorses Cenk Uygur Despite Antigay Misogynist Past.” On Twitter, Guardian columnist Moira Donegan worried that Sanders didn’t “seem to take sexism very seriously.” Where so many of the attacks on Sanders have required ignoring or twisting his record on sex and gender issues, the unambiguity in Uygur’s past comments make it hard to interpret them as anything but objectifying and downright offensive.

There was another problem: The seat Uygur is hoping to fill belonged to Katie Hill, the congresswoman who resigned six weeks ago after the blog RedState leaked nude photos of her, along with evidence of a relationship she had with a campaign staffer. Days later, the House Ethics Committee opened an investigation into allegations she had an inappropriate relationship with a different staffer, one who worked in her congressional office. (She denied that affair.) The whole episode reeked of misogyny and double standards. Hill’s relationship with the staffer had been consensual, which is more than several of her male colleagues could say of allegations levied against them. And the photos, Hill claims, had come from her estranged and allegedly abusive husband. Nonetheless, Hill stepped down in disgrace. This was the fraught territory Uygur entered when he decided to mount a campaign in Hill’s district. Anyone with a trifling command of Google could have seen the risk an endorsement posed for the Sanders campaign: one previously accused of not putting women and people of color first in his campaign endorsing another man with a history of sexist and racist comments who’s running to take a seat vacated by a woman hounded out of Washington by what might have been revenge porn. As POLITICO reported, Sanders’s California campaign staff even warned the national campaign against it.

It’s very possible that Uygur has fully reformed, as he claims. People change. People grow. People regret writing unsavory blogs. No movement can attain political power by demanding sainthood from its adherents. And Uygur’s politics would go a long way towards making the 25th district and this country a more tolerable place. Personally, I would vote for him if I could—his policies mean more to me as a voter, and as a Black woman, than pinky-swear promises that the candidate’s heart is cleansed of all misogyny and temptations to say the n-word. But not everyone sees it the way I do—to many, especially those already skeptical of Sanders, a decades-long record of distasteful comments might be just enough to cloud otherwise good politics. To win a presidential election, Sanders will need to draw those people, too.

If an endorsement is a political chess move, this one seemed destined to take the movement closer to a loss than a win. There is no dearth of down-ballot progressives who could use Sanders’s powerful endorsement at no cost to his chances. Take Jessica Cisneros in Texas, Shahid Buttar in California or McKayla Wilkes in Maryland. The list of challengers from the left is long and growing—thanks in large part to the campaign the senator waged in 2016. Retracting his endorsement of Uygur may have been tough to swallow for progressives, but it was ultimately the right call. The last thing Sanders needs is to fuel the “Bernie Bro” stereotype and the unsubstantiated accusations of sexism that plagued his campaign in 2016.

For all its energy heading into 2020, the left is still in a tenuous position. Calling for transformative changes to the American economy places all leftist candidates in a vulnerable place, in an environment where a political victory is an exception rather than a norm, and where attacks will come from all over the political spectrum to prevent that. The senator and the new era of progressivism that his administration could usher in will be of no use to anyone if he doesn’t actually retake the White House from the Republican Party and the centrist wing of the Democratic Party. It is crucial that Sanders not hand anyone the opportunity to reopen the door to attacks on his character, if he wants to win.