Menachem Pritzker thinks so:
Lon Becker doesn't seem to appreciate the wide spectrum of opinions in Israeli politics. Likud's position happens to be one taken by 22% of the Israeli population, as of the last election. An additional 18% of the population voted for parties further to the right of Likud, so when AIPAC takes positions similar to Likud's, they're aligning themselves pretty close to the median of the Israeli population.
When Labor is in power (And, sorry to tell you, they are in power. Labor, under Ehud Barak, is an important member of the coalition), AIPAC still represents a position held by a large number of Israelis. Who, of the Israeli electorate, does J-Street represent? They occasionally find themselves agreeing with Meretz, representing the leftmost 3% of all Jewish voters, but who did they represent when they spoke out against Cast Lead, a defensive war that even Meretz was in favor of?