These are not stupid people. They are serious people. They know, surely, that the construction in contention is in East Jerusalem neighborhoods that threaten to entirely cut off 300,000 Palestinians from their families and commercial opportunities in the West Bank. They know that any effort to keep these neighborhoods, or preserve the status quo, will result in Bosnian style violence. They know that this violence would further undermine American interests in the region.
They know that 41% of Israelis (its professional elites, disproportionately) oppose this construction, even if a slightly larger number favor it, so that, at best, continuing Netanyahu's policy will tear the country apart. They know that Israeli governments have wasted $17 billion on a settlement project that might have been invested in Israel proper, including West Jerusalem. They know that Israel has no way of remaining a democracy if settlements continue and a peace deal, including partition of Jerusalem, is not forthcoming. (Kadima's Haim Ramon followed the report of Netanyahu's speech on Reshet Bet and made all of these points himself.)
They know that, as Ehud Olmert told me himself, he and Palestinian President Abbas had already held advanced discussions over a formula for sharing Jerusalem; that his formula entailed keeping the city physically intact, but allowing Palestinian neighborhoods to revert to the sovereignty of a Palestinian state, while the Holy Basin fell under the custodianship of Israel, the United States, and Arab countries, including Palestine. They know that Jerusalem would, ideally, be a capital for two highly interdependent states; and that whether or not Jerusalem will be an international city in any formal sense, its security in the long run will require the presence of international forces.
They also know, finally, that American Jews have about as much in common with King David's iron age Israelites as American Chinese have with the Shang Dynasty. They know that it was the fanaticism and corruption of Judean kingdoms that lost Jerusalem. They know that, since then, normative Judaism has seen Jerusalem as a moral ideal, like Utopia, not a material place; and that Zionism was meant to valorize a modern Jewish nation, not an ancient land. They know that the Passover festival begins next week, and Jews everywhere will explain to their children why freedom is a universal principle. So what exactly were they cheering?
I do not mean to ask this question cynically. There is some kind of hole in the heart that backing Netanyahu over "Jerusalem" seems to be filling. There are intelligent and decent people gathered at AIPAC, and many young people who are eager to stand for something. What is it, other than the insistence that they, who "didn't do anything," fiercely admire Israelis who did something?