A leopard never changes it's spots . The problem is the left has successfully been able to make distinctions between forms of socialism . The truth of the matter is there is not a dime's worth of difference between international or universal socialism (communism) and national socialism(Nazi) . The left has always harbored antisemitism
('Antisemitism and the left: On the return of the Jewish question.' by Robert Fine and Phillip Spencer)
"Universalism has always shown two faces to the world: one emancipatory and inclusionary, the other repressive and exclusionary. Jewish experience of universalism has been correspondingly equivocal. Antisemitism and the left provides an original and stimulating study of modern antisemitism, tracing the intellectual and political struggles between these two opposed perspectives. At times, universalism has acted as a stimulus for Jewish emancipation, for civil, political and social inclusion. But it has also been used to justify hatred of Jews, depicting them as hostile to the entire human race, in ways even more sinister than those found in pre-modern and largely Christian traditions of anti-Judaism. A key feature of this repressive and exclusionary universalism and the distinctly modern form of antisemitism it has generated has been the construction of a putative 'Jewish question', which somehow needs to be 'solved'.
Antisemitism and the left (oapen.org)
Zionism and Israel(a so called modern imperial colonial state ) has just given them an excuse to brush off their hatreds .
The left forgets that it was Lenin and Stalin who claimed Jewish was not a national identity ;and that Jews did not deserve their own state.
"The question of national autonomy for the Russian Jews consequently assumes a somewhat curious character: autonomy is being proposed for a nation whose future is denied and whose existence has still to be proved!”
(Lenin )
It makes sense . Jewish as a national identity is completely at odds with the left's vision of abolishment of the national state .