Despite a presentation to Jewish leaders here last week that sought to refute statistics that indicate the soaring Palestinian birthrate will threaten the character of the Jewish state unless the Palestinians get their own state, not everyone is convinced.

“It was an incredibly detailed presentation,” said Malcolm Hoenlein, executive vice chairman of the Conference of Presidents of Major American Jewish Organizations. “On our mission [next month to Israel] we’ll have a presentation by those who have a different viewpoint.”

Rabbi Eric Yoffie, president of the Union of Reform Judaism, said he was unable to attend the briefing but had questions about the authors’ credentials.

“I don’t know who they are,” he said. “They shouldn’t be there unless they have impeccable academic credentials. Whether they do or not I don’t know.”

The American-based project was led by Bennett Zimmerman, a former strategy consultant with Bain & Company, a management consultant firm; historian Roberta Seid, and Michael Wise, identified as an expert in mathematic modeling techniques. Yoram Ettinger, a persistent critic of Israeli Prime Minister Ariel Sharon’s peace moves who calls the Gaza pullout “a giveaway,” was a strategic consultant on the project.

The essence of their report is that there are not 3.8 million Palestinians living in the territories, as some Israeli demographers contend, but rather 2.4 million. They said the Israeli figure does not include emigration from the territories and a documented drop in the Palestinian birthrate, while including 300,000 Palestinian expatriates living abroad and 200,000 Palestinians living in East Jerusalem who are also counted in the Israeli census.

Media reports said their research has been accepted by prominent American demographers Nicholas Eberstadt and Murray Feshbach.

But Israeli demographer Sergio della Pergola told the Israeli newspaper Haaretz that he rejected the new study. He said its figures were distorted.

Uzi Dayan, who served from 2000 to 2002 as national security adviser for Prime Ministers Ehud Barak and Ariel Sharon, said he is convinced the Israeli demographic studies are correct. He said that Jews now comprise 52 or 53 percent of the 10.5 million people living in Israel and the territories. And he said that the figure is expected to drop to 45 percent by 2020.

“Palestinians are returning to the West Bank in significant numbers,” he said.

But Rabbi Yoffie said whether there are 1.5 million fewer Palestinians or not is irrelevant.

“It doesn’t make any difference whether or not the Arabs are going to be a majority in 10 years or constitute 40 percent of the population in 10 years,” he said. “A Jewish state needs ... as Shimon Peres says, a secure majority and not a trembling majority.”