In the battle for influence in the Middle East, Israel retains one unrivaled weapon in its arsenal: American voters.

While other nations spend millions hiring high-priced lobbyists, Israel can rely on a grass-roots army of thousands of supporters to achieve its priorities. Those foot soldiers have helped make Israel the top recipient of US foreign aid since World War II and ensured that the country’s existential priorities — notably Iran’s nuclear program — are America’s as well.

At the center of that effort is the half-century-old American Israel Public Affairs Committee, self-identified as “America’s pro-Israel lobby.” AIPAC, which boasts more than 100,000 members, spends well north of $60 million a year to promote “strong US/Israel ties” — including almost $3 million lobbying Congress and the executive branch last year.

AIPAC isn’t a political action committee and doesn’t directly fund any electoral campaigns. A bevvy of pro-Israel groups, however, spent more than $8.8 million on Congressional candidates in 2012-2013, according to an analysis by the nonprofit MapLight; their top recipient, with $747,000, was Sen. Mark Kirk, R-Ill., the co-sponsor of Iran sanctions legislation and one of AIPAC’s strongest allies in Congress.