For the past half century, the American Israel Public Affairs Committee (AIPAC) largely held sway in elections in both political parties. They threatened and intimidated those who opposed them and, when a critic of Israel was defeated, they boasted of victory, holding it up for others as a lesson. Last week’s Democratic primary elections in New York City, in which three insurgent critics of Israeli policies defeated AIPAC-endorsed candidates, point to what may be the end of an era for the pro-Israel lobby.