Rosa Prince is an author and journalist who writes about US and UK politics. She is the author of the book " Comrade Corbyn ." The opinions in this article belong to the author.

(CNN) Jeremy Corbyn, the leader of the UK's opposition Labour Party, has an anti-Semitism problem -- and so now does the rest of the United Kingdom.

Long before his election as Labour leader, Corbyn had been viewed with suspicion by some British voters -- both inside and outside his party.

Back then, it didn't seem to matter much. Corbyn was an obscure, if long-serving, backbencher in the House of Commons, never trusted with ministerial office by the Labour prime ministers he served in nothing except name and devoted to an eclectic range of anti-establishment, largely left-wing and anti-capitalist causes.

With his unexpected elevation to the Labour Party's leadership in 2015 , however, those interests came into sharper focus. And to many British Jews -- and non-Jews -- a number appeared unpalatable.

There were the questionable associations with Holocaust deniers and anti-Zionists; self-proclaimed "friendships" with representatives from Hamas and Hezbollah; his stress on inclusive dialogue over the Israel/Palestinian conflict while only ever speaking to one side.

In the intervening 2½ years, the question of whether Corbyn and the Labour Party he leads contains strands of anti-Semitism has bubbled below the surface of British politics, occasionally bursting to the surface in wildly malevolent eruptions.

We are currently in the midst of one such eruption. The latest trigger: the unearthing of Corbyn's disapproval, expressed on social media in 2012, of the painting-over of a mural depicting a crude caricature of Jews and his tone-deaf response to the resulting outcry.

This is only the latest in a series of incidents which, at the very least, have left Corbyn open to charges of tolerating anti-Semitism and anti-Semites.

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When I was researching my biography of Corbyn, a then-member of his leadership campaign confided that aides had repeatedly pleaded with him to address the concerns of Jewish community leaders who were already expressing alarm at the prospect of Corbyn taking charge of a major British political party. The candidate was, I was told, utterly uninterested, seeing, as he often does, any implied criticism as hostility and therefore an unwarranted smear.

This was I think the last interview I conducted before returning home to New York, where I still live. Watching Labour's Jewish crisis unfold from the city with the largest Jewish population in the world after Tel Aviv provides an interesting perspective.

To say that to play fast and loose with anti-Semitism would be a disqualifier for political office in the United States is an understatement.

Even Donald Trump, who makes no bones offending entire racial communities, has in the face of accusations of anti-Semitism resisted doubling down in the manner he does on so many other issues. To do so would be political suicide.

Until recently, the same was true of the UK, too. And, in my opinion, it is a direct result of Corbyn's leadership that it is not.

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At the outset, many Labour moderates assumed Corbyn's victory marked a temporary aberration. It would soon be back to business as usual, a resumption of the party's historic beliefs in a mixed economy and the Atlantic alliance -- including a proud tradition of opposition to anti-Semitism in all its forms.

Instead, Corbyn has grown stronger through his time in office, attracting first hundreds of thousands of enthusiastic new members who have bestowed him with an almost cultlike status, and, more latterly at last year's general election in which the Labour leader once again proved the critics wrong, the support of millions of ordinary British voters.

All found a new appeal in what had hitherto seemed old-fashioned allures: full-blooded socialism, nationalization, anti-globalization.

Sadly, some also seem to have been attracted by the permission they felt -- rightly or wrongly -- Corbyn offered them to view first Zionists and ultimately Jews more generally as both oppressors and class enemies.

The result is the unlikely events we witness today, when, more than 60 years after the Holocaust, a mainstream British politician can be accused of "deliberately baiting" Jews without it significantly affecting either his electoral standing or position as party leader.

And that is the most troubling aspect of the crisis the Labour Party now finds itself in.