The left on both sides of the Atlantic are right to be jubilant at news of 29-year old Congresswoman Alexandria Ocasio-Cortez’s mutually admiring phone call with Jeremy Corbyn last weekend. Corbyn, like Bernie Sanders, is a veteran socialist, and came to surprising prominence in 2015, when he was made leader of Britain’s opposition Labour Party by members frustrated at the party’s rightward drift. Softer liberals willing to stomach AOC’s economic populism as long as she allows US and UK left-wingers to move on from their infatuation with these old white dudes are missing the point. The New Left that produced Sanders and especially Corbyn was streets ahead on antiracism and gender and sexuality, long before today’s diversity agenda made it politically convenient to be so. AOC meanwhile got where she is, not merely by fulfilling a liberal fantasy of diversity, but by showing the same populist grit that kept her elder comrades campaigning all those years.

AOC’s youth, gender, and Puerto Rican heritage allow her to appeal to those Democrats for whom Bernie Sanders’ unanticipated disruption of Hillary Clinton’s coronation placed him on the wrong side of the culture wars. Yet AOC started in politics as an organiser on Sanders’ 2016 presidential campaign, and her own primary campaign against the sitting establishment Democrat, Joseph Crowley, borrowed Sanders’ populist refusal to follow party decorum, as well as his grassroots coalition-forming across the wider left.

This is what makes it so dismaying to see right-wing and liberal commentators treating this meeting as AOC’s first big test: her ‘I know thee not old man’. Asking, that is, whether she will prove herself by dropping the unacceptable face of leftism in the form of Corbyn: in particular in light of his alleged anti-Semitism.

Contrary to these commentators, there is no ‘long, documented history’ of Corbyn’s antisemitism. Rather, there is a collocation of guilt by association of a kind that can be deployed against anyone with Corbyn’s decades of Palestinian advocacy. It is legitimate to claim that Corbyn has sometimes made poor choices in who he has defended and spoken alongside. But the invisibility of Palestine in British political discourse means that few of his accusers have ever been faced with his dilemmas.

Questions about Corbyn’s personal associations would also not have the prominence they do were it not for the new mass membership of half a million members that Corbyn has attracted to Labour, and their ultra-visibility on social media. Like Sanders and AOC, Corbyn would be nothing without this huge movement. Yet, as with the general population, a small minority are demonstrable anti-Semites. More damaging, however, have been the many more committed supporters who, appalled at what they perceive as a smear campaign against Corbyn’s pro-Palestinian activism, have taken to denying anti-Semitism exists in the party altogether. Sometimes this has taken the form of attacking pro-Israel MPs (some Jewish, some not) for speaking out against Corbyn, and it isn’t hard to see how anti-Semitic tropes (‘mixed loyalties’, ‘conspiring with the media’), end up being evoked.

The result is a grim circle of provocation and reaction. Incurious and unbalanced reporting leads Corbyn supporters to double down on claims that it’s all a smear. Corbyn spent Passover with a far-left anti-Zionist group called Jewdas, who the scandalised commentariat were reluctant to mention are themselves practicing Jews. Based on the criticism Corbyn received for once chairing a Holocaust Remembrace Day event witha speaker who denounced Israel on Holocaust Remembrance Day, one would be amazed to learn that the speaker was Hajo Meyer, himself an Auschwitz Survivor. Labour had the nerve to seek to modify the supplementary examples appended to the International Holocaust Remembrance Alliance definition of antisemitism in its own policies: but who would guess from all the outrage that legal scholars across the political spectrum have condemned these examples for shutting down free speech on Israel?

The moral clarity of Corbyn’s accusers among establishment spokespeople for British Jews, meanwhile, was rather muddied in the eyes of many Corbynites by the president of the Board of Deputies of Britsh Jews’ unrepentant support for Donald Trump, despite his dealings with open neo-Nazis; and by the fact that one of the main mouthpieces of the attacks, the Jewish Chronicle, had been similarly hostile to Corbyn’s predecessor, Ed Miliband, himself Jewish. Much has been made of the mere 13% of Jews who voted for Corbyn’s Labour in 2017, but the exact same percentage voted for Miliband two years before.

There was legitimate criticism to be made of Corbyn’s handling of antisemitism, but the press, the Conservative Party, and Corbyn’s own hostile MPs made it hard to keep in sight, by continuously indulging ludicrous conspiracy theories about Corbyn’s sympathy with Putin, his dealings with Czech spies, and his stance on Brexit. No wonder that, to this day, there are some party members who have reached the incorrect conclusion that there is nothing real for Labour to answer for on antisemitism after all.

AOC knows how it hard it can be to have a good faith discussion on Israel-Palestine. After commenting angrily on the Israeli military response to protests on the Gaza border last year, which left 150 largely unarmed Palestinians dead and tens of thousands injured, AOC was pressured into backtracking on her use of the specific terms ‘massacre’ and ‘occupation’ in a t.v. interview. Whatever personal conclusions AOC may have reached (one hopes they were not represented by the deferential interview in question), her original comments were legitimate speech and shouldn’t be apologised for. We are seeing what happens when they are. Last week, two of AOC’s colleagues in the House of Representatives, the Somali-American, Ilhan Omar, and the Palestinian-American, Rashida Tlaib, were branded racists in the respectable press for their support of the Boycott, Divestment and Sanctions movement: their participation in this perfectly legitimate peaceful protest placed on a moral par with the actions of white nationalists and neo-Nazis. Omar is now being denounced as an anti-Semite — by Republicans and Democrats alike — for a glib and defiant reference to donations made by members of the American Israel Public Affairs Committee to pro-Israel politicians.

Labour’s antisemitism woes hardly make taking a bold and unambiguous line on Israel-Palestine an attractive prospect for the emerging US left, as it struggles to establish itself in the wake of Sanders. But the ease with which genuine instances of antisemitism can be blurred with the suppression of legitimate political speech, should spur US progressives to more clarity, not less. Trying to balance Corbyn’s history of highly principled and often unpopular advocacy for the Palestinians, with a cautious and reactive approach to Israel and antisemitism has only damaged what relationship Labour had with many UK Jews, while doing little for Palestinians. AOC and her colleagues should not make the same mistake.