On Monday, Bernie Sanders endorsed Joe Biden for the presidency in a live-streamed virtual appearance with the presumptive nominee from his home in Vermont. “Today,” he said to Biden, “I am asking all Americans—I’m asking every Democrat, I’m asking every independent, I’m asking a lot of Republicans—to come together in this campaign to support your candidacy, which I endorse, to make certain that we defeat somebody who I believe, and I’m speaking just for myself, is the most dangerous president in the modern history of this country.”

This is not a move that ought to have surprised anyone. Sanders endorsed and campaigned for Hillary Clinton in 2016, and his rhetoric about bringing Americans together—including Republicans—to beat Donald Trump has long echoed the rhetoric of traditional Democrats like Biden, striking an often ignored contrast with the tone of his most vocal supporters. Since Sanders dropped out of the race, those supporters have been the subject of heightened consternation among Democrats. Over the last several days, a number of Sanders-backing groups, including campus outposts for the Sanders campaign, local chapters of the Democratic Socialists of America (DSA), and the national DSA organization itself, tweeted their refusals to support Biden. In the DSA’s case, the decision to endorse no Democratic nominee but Sanders had been made and announced at their national convention last year. A tweet from the author Reza Aslan was characteristic of the liberal response: “Breaking news: @DemSocialists endorses Trump for president.”

Naturally, the DSA not only opposes Donald Trump, but includes many members who, in associating Trump explicitly with fascism, have criticized the president in more strident tones than many figures in the Democratic Party. In 2016, the DSA’s national political committee wrote a statement explaining that while the organization would not formally endorse Clinton in the general election, members in swing states were likely to vote for her, and DSA chapters in those states would spend the months before the election focused on a “Dump Trump” campaign that included efforts to register black and Latino voters. The organization hasn’t announced its plans for this year’s general election, but a similar course of action seems probable.

There’s been a suggestion that the DSA’s refusal to back Biden illustrates the left’s naiveté about transactional politics. “Why did Bernie lose?” Tablet’s Yair Rosenberg asked on Twitter. “In part because some on the left prioritize self-righteous symbolism over political power and influence. The DSA preemptively expelling themselves from the tent of the only presidential candidate with a chance of hearing or being pressured by their ideas is that.” The notion that an organization set on abolishing capitalism would have otherwise had a meaningful place inside the tent of the Biden campaign is entirely too silly to merit an earnest response, but the embedded argument about political influence is worth unpacking for a moment.

Most advocacy groups promise those who offer their engagement and money an opportunity to get closer to the political system. The reward for backing the Sierra Club or the NRA is the knowledge that your issue of interest is being advanced through traditional channels by lobbyists and others with plenty of access to politicians, their campaigns, and the policymaking process. The DSA has promised its members exactly the opposite—that it is an organization not only working to build a movement outside the political system, but also bent on tearing that system down. On this basis, it has grown dramatically in members and in prominence over the past several years—from a state of total political irrelevance to a position of enough significance that mainstream political commentators can declare themselves upset about its pronouncements.