A foreign policy expert consulted by Senator Barack Obama, the leading contender for the Democratic presidential nomination, has accused members of the American Jewish establishment of "McCarthyism" in its attitude towards critics of Israel.
Zbigniew Brzezinski, a former national security adviser, said that the pro-Israel lobby in the US was too powerful, while the slur of anti-Semitism was too readily used whenever its power was called into question.
Presenting a solution for the Middle East, he listed historical compromises that had to be made by Israelis and Palestinians but accused the American Israel Public Affairs Committee (Aipac) – the largest and most influential Jewish lobby group – of obstructing peace efforts.
He said: "Aipac has consistently opposed a two-state solution and a lot of members of Congress have been intimidated and I don't think that's healthy."
He added that other country-specific lobbies, such as the Cuban-Americans, the Armenians and the Irish, had also exerted undue influence in Washington.
Mr Brzezinski, who served under President Jimmy Carter, was a key player in the 1978 Camp David Accords and remains an important voice in the US foreign policy establishment.
An active author and analyst at 80, he is close enough to Mr Obama that his remarks may feed fears in the American-Jewish community that the senator would soften America's traditional strong pro-Israeli stance if he became president.
This perception has been created in part by Mr Obama's professed willingness to talk to Iran and partly by other foreign policy associates.