Some of the planned sites, like the Sixth & I Historic Synagogue, a cultural center in Washington, would have been host of an event if Mr. Mearsheimer and Mr. Walt appeared with opponents, said Esther Foer, the executive director.

Mr. Walt said, “Part of the game is to portray us as so extreme that we have to be balanced by someone from the ‘other side.’ ” Besides, he added, when you’re promoting a book, you want to present your ideas without appearing with someone who is trying to discredit you.

As for City University, Aoibheann Sweeney, director of the Center for the Humanities, said, “I looked at the introduction, and I didn’t feel that the book was saying things differently enough” from the original article. Ms. Sweeney, who said she had consulted with others at City University, acknowledged that they had begun planning for an event in September moderated by J. J. Goldberg, the editor of The Forward, a leading American Jewish weekly, but once he chose not to participate, she decided to pass. Mr. Goldberg, who was traveling in Israel, said in a telephone interview that “there should be more of an open debate.” But appearing alone with the authors would have given the impression that The Forward was presenting the event and thereby endorsing the book, he said, and he did not want to do that. A discussion with other speakers of differing views would have been different, he added.

“I don’t think the book is very good,” said Mr. Goldberg, who said he read a copy of the manuscript about six weeks ago. “They haven’t really done original research. They haven’t talked to the people who are being lobbied or those doing the lobbying.”

Overall Mr. Mearsheimer said he thinks the response to their views will be “less ferocious than last time, because it’s becoming increasingly difficult to make the argument in a convincing way that anyone who criticizes the lobby or Israel is an anti-Semite or a self-hating Jew.” Both Mr. Mearsheimer and Mr. Walt pointed to the growing dissatisfaction with the war in Iraq, criticism of Israel’s war in Lebanon and the publication of former President Jimmy Carter’s book “Palestine: Peace Not Apartheid” as making it somewhat easier to criticize Israel openly.

“This isn’t a cabal; this isn’t anything secretive,” Mr. Walt said.

American Jews who lobby on Israel’s behalf are not all that different from the National Rifle Association, the anti-tax movement, AARP or the American Petroleum Institute, he said, “They just happen to be really good at it.”

“It’s the way American politics work,” he continued. “Sometimes powerful interest groups get what they want, and it’s not good for the country as a whole. I would say that about the farm lobby and about the Cuba lobby.”