Matt Yglesias on lobbies in general:
The strength of these lobbies comes from their passionate commitment to their cause, from excellent organizing skills, and from their ability to unify around it across religious and ideological boundaries, and above all from ability to leverage support serially on issues from likely allies. Thus, the leadership can arrange for millions of protest emails to be sent by evangelical Christians as well as by Jewish congregations. The New Republic takes the same side as Commentary. They succeed even though their most passionate projects are not supported, and are even opposed, by probably a majority of the American Jewish community. I doubt much hangs on money per se; real lobbying is often a relatively inexpensive affair. But behind-the-scenes concurrence of big players like the military-industrial complex on the desirability for a war is crucial if you are a lobby trying to get up a war for other reasons. They are very good at getting their way, and can think and plan carefully a good decade out, and have virtually no effective opposition, which is the real secret of their strength. Did Obama get even 5,000 emails complaining that he did not stand by Freeman? And that would be a tiny number compared to what Freeman's opponents can muster.
[On the subject of statistics showing broad popular support for farm subsidies, though experts use it as the classic economic case of an intensely interested and dedicated group prevailing to create laws that have greater but more widely dispersed costs on the rest of the population]
Still, it seems to indicate that this is a bit more than a question of a narrow group blocking change. What may be happening is that since farm subsidies have passionate defenders in both parties, a wide swathe of people are accustomed to seeing them endorsed by leaders they trust.
With these illustrations of the lobbying process in mind, I'd like to address the mechanisms by which US policy has become today, I'd say very counter productively for US interests generally, committed to ensuring the viability of Israel as a Jewish state.
There are some mostly Jewish supporters of Israel who reflexively identify very personally with the idea that there is and should be a Jewish state in Palestine. Some of those friends of Israel perceive any expression of doubt in the justice of Israel's creation, existence or maintenance as attacks on them personally and attacks on Judaism in general. This feeling of attack leads to a sincere belief that the person who triggered this feeling hates Jews and is anti-Semitic. To a reader disposed to feel this way, I can only imagine that this essay will be perceived as claiming Jews have perniciously taken advantage of non-Jews. I'll say in advance that that is not my argument and not my belief. While I do not agree that there should be a Jewish state in Palestine, I do not mean that as an attack on the reader, the Jewish religion or the Jewish people of Israel.
At its base, the pro-Israel lobby is a regular lobby, not different from the corn products lobby or the lobby of American retired people. Regular lobbies exist because they are effective at steering policy in the fields they care about. To that base of being a generic lobby, there are some other factors that make the pro-Israel lobby especially effective. They are, in order of importance: the fact that US Jews are a particularly wealthy, well educated and influential group generally, defensiveness around charges of anti-Semitism on the part of some US non-Jews, racism on the parts of some US non-Jews, and convergent beliefs on the part of some US Christians.
The textbook explanation of what lobbies represent is that in situations where there are concentrated benefits to a policy and dispersed costs, those who would reap the benefits are more strongly motivated to enact that policy than those who would pay the costs are to prevent the policy. Agricultural subsidies are one widely used example, they slightly increase the level of taxes for the entire economy, but they direct large payments to the farmers. Another common example is steel tariffs. They increase the costs of many goods, impacting nearly every consumer but increase the amount of resources the economy directs at a smaller segment of the economy.
Often it can be shown that the total of the costs, the amount more that the consumers pay for food or appliances using steel, if added up, are greater than the totaled up benefits to the farmers or participants in the steel producing industry. This is not to say that the farmers or steel makers are immoral in any way. To the degree it is a defect, it is a defect inherent in a political system in which the subjects are able to participate freely. Nobody ever says the prescription is to ban lobbies or attack them for being lobbies.
On the other hand, a supporter of steel tariffs could tell a story about people who work in the steel industry who have money to go to Disneyland, and point to others who get haircuts and claim that steel tariffs are broadly beneficial because of the income they ultimately direct towards California amusement parks and barbers. While it is true that even distortions of the economy can be shown to be locally beneficial to other aspects of the economy, that is not an argument that overall the steel tariffs that clearly benefit steel-towns in Pennsylvania are primarily enacted to advance the interests of amusement parks.
We often read that Israel, for example, was able to return the Sinai to Egypt which helped turn Egypt pro-American. Other than Israel, there had never been a reason for Egypt not to be pro-American. Like a farmer helping the economy by getting a haircut partly using government payments, the barber, overall, would have been better off paying less in taxes. Purely from the standpoint of relations with Egypt, the US would have been far, far better off never supporting Israel in the first place.
It is not anti-farmer, just as it is not anti-Semitic to ask the question, if the lobby isn't delivering higher profits to the farms than what would be reflected by market mechanisms, then what is it doing? This is nothing to be ashamed of, nothing to be defensive about, nothing to deny. That is what interest groups do in democracies.
In addition to the fact that the pro-Israel lobby is a lobby, and it pressures policy in a consistent direction away from where it would be in the absence of the lobby, the pro-Israel lobby is especially effective for several reasons. One is that many US Jews feel a strong personal attachment to Israel. Jewish Americans are, in total, the United States' most wealthy ethnic group. They are disproportionately represented in US politics and in some cultural spheres of influence.
The disproportionate Jewish representation in politics is multiplied by the fact that Middle East foreign policy feels more important to many US Jews than it does to many US non-Jews and therefore attracts a further disproportionate Jewish representation in especially that aspect of US foreign policy.
The fact that the Jewish community is wealthy somewhat increases the amount of resources available to the pro-Israel lobby. Two factors may be as important or more important in the special effectiveness of the pro-Israel lobby in strengthening the US commitment to the long-term existence of a Jewish state. One is that even non-Jewish members of the US foreign policy community develop their careers working disproportionately with Jewish members of that community.
By engaging daily with people who feel a strong attachment to Israel, non-Jewish Americans who work in Middle East policy often are shaped in the development of their views to be more pro-Israel than Americans who do not work in that field are.
The second factor is that supporters of Israel have played a gate-keeper role in the dissemination of information about the Middle East to Americans. Just as many people get their views on agricultural policy from people they trust but who have been guided by the agriculture lobby, many US citizens get their ideas of the Middle East from sources that have some bias towards the existence of a Jewish state.
This is not pernicious or the result of some conspiracy held in secret lodges somewhere. But if the people who care enough to become experts exhibit a bias, that bias can be extended throughout the population. Parenthetically, one impact of the internet is that there is a larger and more representative group of gatekeepers now. It is now commonly understood that Mahmoud Ahmadinejad did not threaten Israel with genocide with the "wiped off the map" statement. Ten years earlier it would have been far easier for a story that disparaged one of Israel's rivals to stand undisputed.
So I hope it is not perceived as anti-Semitic that I argue that Jewish Americans are well placed to form the basis of an especially effective lobby. Another factor in making the lobby more effective than it otherwise would be is that many non-Jewish Americans are defensive about charges of anti-Semitism. Jewish people often sincerely perceive attacks on Israel as attacks on themselves, as attacks on Judaism, and therefore anti-Semitism by definition.
Rational or irrational, it is uncomfortable to be sincerely accused of anti-Semitism. To avoid this accusation, non-Jewish Americans often are willing to go further out of their way to defend the existence of a Jewish state than they would in the absence of this potential accusation.
Another factor is that some Americans, not most but an amount that is still significant even if less than when Israel was founded, identify with Israeli Jews more closely than they do with Palestinian Arabs. Possibly Islam is perceived as more "foreign" to Americans than Judaism. Possibly the fact that many of Israel's Jews descend from Europeans while Arabs are "browner" triggers the ability of some US racists to empathize more strongly with Israel's Jews than they do with Arabs.
10% of the US electorate still believe the false story that Barack Obama is Muslim, this story was only spread as true by people (whether pro-Clinton or pro-McCain) who believed that being Muslim would convince some voters to oppose Obama. Possibly that can serve as an estimate of the pervasiveness of anti-Muslim bigotry in the US. It is not overwhelming and could not explain US support for Israel by itself, but it is a factor to consider.
The last factor that strengthens the effectiveness of the pro-Israel lobby is that support for Israel aligns with the religious beliefs of some Christians. Much is said about the idea that prophecy must be fulfilled according to some beliefs. Beyond that, Christian churches use the Old Testament of the Bible, which relates the story of the Jewish people and forms part of the holy books of today's Jews as a primary text. Christians do not have a similar relationship with any Muslim book. Even beyond prophecy Islam may well be more religiously foreign to US Christians than Judaism.
The United States has the right to dedicate its resources to ensuring that Israel has a permanent Jewish majority if it chooses. This course that the United States is currently taking, to the detriment of its other foreign policy interests, has so far been extraordinarily expensive and has caused a tremendous amount of misery in the region. The misery ranges from the hundreds of thousands of Iraqis who went without purified water during Iraq's sanctions, to those Iranians who are unemployed because of US efforts to deny capital to the Iranian economy, to the Egyptians who are not able to participate in their political system, as well as the Saudis and Jordanians - with US support and connivance. US efforts to ensure that none of Israel's neighbors are ever in a position to effectively challenge Israel's legitimacy as a Jewish state takes a very large toll on the people of the region.
Tempering down the reaction throughout the region to the US taking the position it takes is hugely expensive, far in excess of the 3 or so billion in direct or nearly direct transfers to Israel every year. 9/11 was in large part a strike from Israel's region in reaction to US policies aimed at ensuring the long-term viability of Israel as a Jewish state. No other region of the world is nearly as hostile towards the US as that region. The US efforts to manage this regional hostility, including the costs of occupying both Iraq and Afghanistan, and also including the pressures the US is putting on Pakistan, are costs the US bears basically because of the effectiveness of the pro-Israel lobby.
So to answer the question of the title, Jews do not control America in crude caricature way that friends of Israel often dismiss as anti-Semitic. But US foreign policy is consistently guided further in the direction of defending the existence and viability of a Jewish state than it would if there was no lobby. The lobby is very effective at moving the United States away from policies that would better align with US interests and its core values.