J Street and it's newly formed nemesis, Emergency Committee for Israel (ECI) are carving out left and right-wing territory within mainstream American electoral politics and I don't think this will be "good for the Jews".
Why? Each organization in its own way further's the delegitimizers' goals. They each have their own set of Good Jews/Bad Jews. And they fight it out around the election campaigns of national candidates.
For J Street any old Two-State Solution will do and they pay scant lip service to Palestinian intransigence and Israel's security. ECI, on the other hand, pays no attention to disagreements within Israel, and supports the most rejectionist line within the government.
J Street does very little to counter anti-Israel campaigns such as BDS, and will not distance itself from the Jewish anti-Zionists groups groping at it's edges.
ECI, fathered by Bill Kristol and Gary Bauer (now there's a visual) reinforces the delegitimiers' claims that support for Israel is a right-wing phenomenon. Do we really want Sarah Palin coming to Israel's defense?
Both orgs are forcing Jewish Americans to divide their political allegiances entirely on the basis of support for Israel. Say what you will about ADL, AJC, etc., their 503c status kept them from declaring for candidates. These new guys' tactics seem just too unseemly.
J Street ad for Joe Sestak
ECI ad against Joe Sestak