The Israeli lobby does not have the field to itself. On any given issue, it may be opposed by a variety of interest groups unrelated to the Middle East (e.g., conservative groups that have nothing against Israel, but oppose foreign aid on principle), but its main rival is the Arab lobby, which similarly consists of those formal and informal actors that attempt to influence U.S. foreign policy to support the interests of the Arab states in the Middle East.
As a result, Jews have devoted themselves to politics with almost religious fervor. This is reflected by the fact that Jews have the highest percentage voter turnout of any ethnic group. The Jewish vote also matters because the population is concentrated in key states. Though the Jewish population in the United States is only about six million (about 2.3% of the total U.S. population), the 10 states with the highest concentration of Jews are worth 244 of the 270 electoral votes needed to elect the president. If you add the non-Jews shown by opinion polls to be as pro-Israel as Jews, it is clear Israel has the support of one of the largest veto groups in the country.
