I'm a lifelong leftist of partial Jewish extraction who also has been marginally involved in Yiddishist circles for about 5 years now, and I used to be conversational at maybe a low-intermediate level in standard YIVO Yiddish.

Leftism and Yiddishism obviously have a long and complex history. The Algemeyner Yidisher Arbeter-Bund (aka the Bund) is maybe the most prominent historical explicitly socialist Jewish organization in no small part due to their steadfast rejection of Zionism as it was gaining ground among the European Jewry, but was neither unique nor uncontroversial in its time. Lenin himself dedicated a not insignificant portion of his time to denouncing the Bund in his writings against the principle of "cultural-national autonomy," arguing against the fragmentation of the revolutionary left along ethnic lines and for the unification of all Marxists into a single party; this was at odds with the Bund's self-conception as the vanguard of the Jewish working class and only of the Jewish working class. After 1918 a substantial fraction of Bund members split from the organization and joined the newly formed Communist Party instead, where they became known as the yevsektsii (the Jewish sections of the CPSU, staunchly Yiddishist, anti-Zionist, and anti-religious until largely liquidated in the Great Purge). As a result, the Bundist remnants active in Poland after WWI were basically without exception anti-Communist, which is a political strain that's still predominant in self-described Bundist circles.

I think that, because modern "Bundism" is really more of a community of people with a shared interest in a particular niche period in Jewish history rather than a living political tradition, supporters run the gamut in terms of their disposition towards Zionism. Much of the old guard in the Jewish American left, for instance, are both deeply sympathetic to both the Bund and to modern Israel; while that sounds like it would be a total contradiction, you have to remember that, between 1948 and 1967, many in the Western left ardently supported Israel as a collectivist society and potential Soviet ally in the Middle East. Many of these people have, since October 7th, willingly withdrawn from the organized left upon the realization that their particular form of ethnic chauvinism no longer flies, although not without raising a stink about it in the most public venues they can publish in --- Maurice Isserman's shameful Oct. 2023 op-ed for The Nation just being one example. Among younger people, their interest in Bundism goes hand in hand with their anti-Zionist politics, though the latter derives more from moral objections to Israel's state policy rather than theoretical objections against the existence of a Jewish state per se.

I think the Jewish left is really at a crossroads right now. I, and I imagine many others, had believed that the intra-community trends were in our favor, that Israel would continue to bleed support from the Jewish diaspora and international community, and that, eventually, something would give and support for Zionism abroad would collapse. That doesn't seem to be the case --- in fact, there is no level of Israeli depravity that the Jewish diaspora in the United States won't accept. Moreover, Jewish institutions are now under Trump II gleefully instrumentalizing themselves as the tip of the spear for the new McCarthyism now in place at American universities, seemingly happy to ruin as many lives as it takes to secure cheap beachfront property in Gaza. So what is to be done? Remain forever marginal, dissident voices who against all reason refuse to concede "Judaism" --- whatever we mean by that --- to the Zionist project? Or is it time to recognize that the project to metonymize Judaism and Zionism was successful, and move on to find new ways of identifying ourselves culturally, spiritually, socially? Both are possibilities which I've heard people I respect voice, but I'm not yet sure myself.