American Jews mostly track well to the left of general American public opinion on Israel, just as American Jews by and large are more liberal than their fellow citizens on many other public policy questions.
A sturdy majority of non-Jewish Americans support Israel for reasons that have nothing, repeat nothing, to do with the generally more liberal and nuanced views of American Jews.
Roger Cohen, Joe Klein, and Tom Friedman are, for example, considerably more critical of Israel than, say, Bill O’Reilly, Rush Limbaugh, Glenn Beck and Sean Hannity. David Remnick’s New Yorker doesn’t read much like a Likud PR outlet. The New York Review of Books stands, if anything, a bit to the left of J Street on Middle East issues.
The mainstream American Jewish journalistic establishment is firmly anti-Likud; the Jewish side of Hollywood is almost vituperatively anti-Likud;
To the extent that there is an American Jewish establishment, that establishment favors J Street style ideas.
Individual Jews and predominantly Jewish organizations like AIPAC derive their influence over American foreign policy not from their Jewishness, but from the affinity of their policy agenda with the views and priorities of America’s non-Jews. When American Jews say things about the Middle East that resonate with the views of American non-Jews, they are influential. When, as in the case of the persistent agitation to free convicted spy Jonathan Pollard, Jewish conservative supporters of Israel deviate from the gentile consensus, that influence suddenly disappears.