With the Mearsheimer and Walt book "The Israel Lobby" due out next month, I thought I'd preemptively discuss "the anti-Israel Lobby," using a similarly broad definition for the "anti-Israel Lobby" as M & W do for the "Israel Lobby". In the United States, the presumptive anti-Israel lobby includes the 20% or so of Americans who are strongly anti-Semitic, the National Council of Churches, the Middle East Studies Association, the oil industry, many former state department officials who served in Arab countries, businesspeople with close ties to Arab countries, Muslim and Arab-American organizations, major elements of the ideological Left (including NGOs like Human Rights Watch and Amnesty International that falsely claim not to be part of the ideological left), and the Buchananite right.
Looking more broadly worldwide, we have the dozens of Arab and Muslim nations, the 15-30% (depending on what study you look at) or so of Europeans who are strongly anti-Semitic, the foreign services of most European nations (there was a great Yes, Prime Minister episode years ago joking that the British Foreign Office still thinks of Israel as Palestine, and that the true enemy of the British is not the Soviet Union but the French), the far left, including the Hugo Chavezes of the world, the far right, many multinational companies with a great deal of business in the Arab and Muslim world, the large and influential Muslim populations in many European nations, and so on. Plus, supporters of Israel have to deal with the fact that two of the most powerful empires of the 20th century, Nazi Germany and the Soviet Union, fomented both anti-Semitism and anti-Zionism throughout the world as an intrinsic part of their ideology, and that the legacy of both of these nations' propaganda efforts are still manifest. Not to mention the continued salience of traditional Christian and Muslim anti-Semitism.
Overall, the odds are stacked against Israel's allies, even in the U.S.--the anti-Semites alone easily outnumber the pro-Israel Jews and evangelicals (not all evangelicals are pro-Israel--see Jimmy Carter--and some of them are anti-Semitic). In my views, the pro-Israel sentiment nevertheless prevails primarily because Israel has a much better case than does its enemies. The odds are so overwhelming against Israel in much of the rest of the world that it's hardly surprising that the case for Israel to a large extent gets drowned out, especially when the case for Israel as a liberal democracy has relatively little salience in theocracies and autocracies.
The long and the short of it is, first, that if Mearsheimer and Walt fail to explain the scope and nature of the anti-Israel lobby, the book will clearly be a screed, not a serious scholarly work (and it may be regardless, of course). Second, opponents of Israel seem to think that pointing out the purported power of the so-called "Israel Lobby" will somehow shame Israel's friends into shutting up. But if one recognizes the heavy odds facing Israel's friends--what other group trying to influence public policy has to fight such a massive array of determined enemies?--I think it's clear that, as Alan Dershowitz wrote years ago in a broader context, what is really needed is even more chutzpah.
UPDATE: To avoid any inadvertent subtlety, the point is that if no "Israel lobby" existed, American Middle East policy would not be dictated by neutral, nonideological considerations of American national interest, but by the concerns of the "anti-Israel lobby," who have ideological and self-interested reasons to be anti-Israel, just as is in the rest of the world. M & W themselves have made it clear in their "Israel Lobby" paper and elsewhere that they harbor a distaste for Israel quite apart from what they consider to be America's national interest ("Viewed objectively, [Israel's] past and present conduct offers no moral basis for privileging it over the Palestinians.") If Mearsheimer and Walt don't come up with a good reason why friends of Israel should leave the field to the anti-Israel lobby, including M&W themselves, I can't see much of a point to their book.