"Among respondents to the survey commissioned by the Jewish Electorate Institute, a group led by prominent Jewish Democrats, 34 percent agreed that “Israel’s treatment of Palestinians is similar to racism in the United States,” 25 percent agreed that “Israel is an apartheid state” and 22 percent agreed that “Israel is committing genocide against the Palestinians.”
Among younger voters included in the survey released Tuesday, agreement with those statements was higher, though still in the minority."
How large a proportion? Let's see some numbers of American Jews who think Israel is apartheid and a racist ethnostate.
https://www.haaretz.com/us-news/a-quarter-of-u-s-jews-agree-that-israel-is-an-apartheid-state-in-new-survey-1.9995986
"Among respondents to the survey commissioned by the Jewish Electorate Institute, a group led by prominent Jewish Democrats, 34 percent agreed that “Israel’s treatment of Palestinians is similar to racism in the United States,” 25 percent agreed that “Israel is an apartheid state” and 22 percent agreed that “Israel is committing genocide against the Palestinians.”
Among younger voters included in the survey released Tuesday, agreement with those statements was higher, though still in the minority."
I've never heard of this group and this one poll, but even if we take it at face value, the overwhelming majority of US Jews reject James' smears.