First, just a tiny, little change. "The international Jewish community has a stranglehold on the American Congress." It's really not much of a change in meaning, so, perhaps being generous we might call it a tiny bit less antisemitic.
"Zionists have a stranglehold on the US Congress." Probably worse than "The international Jewish community..."
"The Israel lobby has a stranglehold on the American Congress." It's not immediately clear to me (based on just the words themselves) that this statement is even meant to be any different in content than any of those above, except that it's meant to not be understood as antisemitic. But if it isn't immediately clear that the content is significantly different, shouldn't we be at least a little suspicious?
Yet, I think a lot of people would have immediately thought to themselves that the statement is fundamentally different. Mearsheimer and Walt put it this way in their famous article on the Israel lobby London Review of Books:
The bottom line is that AIPAC, a de facto agent for a foreign government, has a stranglehold on Congress, with the result that US policy towards Israel is not debated there, even though that policy has important consequences for the entire world.Well, they say "AIPAC" rather than "the Israel Lobby," but I don't think that's really so important. At once it's a more concretely defined object, but obviously less powerful than "organized Jewry" could be. And if we recognize that we ought not to say that organized Jewry controls Congress, why would we think that it makes so much more sense to say that a less powerful group has that much power. Ultimately, M&W rely on the full "Israel lobby" to try to explain AIPAC's power, anyway, so it becomes the same with a simple, logical substitution. (The phrase "de facto agent for a foreign government" is also really problematic, but we'll save that for another time.) A lot of people wrote that no matter how much antisemites might enjoy and profit from Mearsheimer and Walt's work, it's clearly not antisemitic.
But how can this be clearly not antisemitic if the only difference is a (superficial?) substitution of a few words. In a world where Canadian can be used to mean "black", how can we ever think that substituting just a few words could change meaning so much as to render such a statement objectively and unquestionably not antisemitic? Instead, I think it would serve us well to recognize that Israel often functions in the same was as "World Jewry" used to within antisemitism. So, if substituting one for the other makes a statement blatantly conspiratorial, we should probably be especially aware of the possibility.