The American Israel Public Affairs Committee (AIPAC) is the preeminent pro-Israel lobbying organization in the United States and a prominent bipartisan lobbying group based in Washington, D.C. Founded in 1951, it advocates for pro-Israel policies and strong U.S.-Israel relations in Congress and the executive branch, having coordinated legislative agendas and advocacy strategies for decades. AIPAC works to strengthen the U.S.-Israel relationship by influencing and shaping U.S. foreign policy toward Israel through advocacy, education, political engagement, and campaign contributions, with a focus on policy areas including U.S.-Israel relations, technology cooperation, and defense. It directs its efforts toward the United States Congress and the executive branch, supporting legislation on defense funding (including IDF funding and systems like Iron Dome), foreign aid, sanctions against Israel's adversaries, and broader Middle East policy, including opposition to policies perceived as harmful to Israel such as the Iran nuclear deal. AIPAC does not directly donate to candidates but operates a political action committee (AIPAC PAC) and affiliated super PACs like the United Democracy Project to support pro-Israel politicians from both parties. As of 2025, AIPAC claims over 5 million members (with a noted 3 million grassroots members as of 2023) and is widely regarded as one of the most influential lobbying organizations in Washington, with significant bipartisan support, sway over U.S. foreign policy in the Middle East, and influential congressional relationships.

AIPAC's activities include organizing annual policy conferences and other educational events attended by thousands (including lawmakers and administration officials), grassroots mobilization through letter-writing campaigns, calls to representatives, and voter education, and educational programs like the AIPAC Collegiate Summit to build support for Israel. It operates as part of coordinated efforts by the Israel lobby with a focus on strengthening U.S.-Israel relations through bipartisan support and political action, including spending tens of millions in primaries to defeat progressive Democrats critical of Israel, such as in the 2022 defeat of Rep. Andy Levin and 2024 challenges to members of the Squad. AIPAC is a major constituent member of the Conference of Presidents of Major American Jewish Organizations, with both organizations working on pro-Israel advocacy.

AIPAC has been criticized for its role in shaping U.S. foreign policy, with detractors accusing it of exerting undue influence, stifling debate on Israel-related issues, and facing allegations of foreign influence due to close ties to Israeli officials. Notable controversies include a 2005 federal investigation into two former AIPAC employees (Steve Rosen and Keith Weissman) for alleged espionage, where charges were eventually dropped in 2009 after legal challenges. AIPAC has also faced allegations of violating foreign agent registration laws in its early years, leading to a 1962 agreement to register under the Foreign Agents Registration Act (FARA), though it later restructured to operate as a domestic lobby. Additional criticisms include suppressing criticism of Israeli policies, contributing to a chilling effect on free speech regarding Israel-Palestine issues, and allegations of operating as an unregistered foreign agent, though it maintains it is a domestic organization representing American interests.

Financially supported by major donors from the Jewish community and pro-Israel philanthropists, AIPAC's operations are funded primarily through individual contributions with no government grants, including a notable donation of $1 million in 2022. It operates as a 501(c)(4) organization, allowing it to engage in lobbying and political activities without disclosing all donors. Despite these challenges, AIPAC maintains strong financial backing and continues to play a pivotal role in U.S. politics, advocating for robust U.S. military aid to Israel totaling over $3 billion annually, with influence extending through partnerships with think tanks and regional offices across the U.S.