“For the sake of peace, the world must not allow Iran to have a nuclear weapon,” she said.

Prime Minister Ehud Olmert of Israel, on the other hand, put all options on the table. “The Iranian threat must be stopped by all possible means,” he said Tuesday evening, speaking to the same group. “The international community has a duty and responsibility to clarify to Iran, through drastic measures, that the repercussions of their continued pursuit of nuclear weapons will be devastating.”

Mr. Olmert also called for international sanctions against Iran to be toughened. He did not specifically mention military strikes, but did say that “Israel will not tolerate the possibility of a nuclear Iran, and neither should any country in the free world.”

Mr. Olmert is scheduled to meet with President Bush at the White House on Wednesday.

The issue of opening high-level diplomatic talks with Iran has come under the spotlight this political season, and that has played out at Aipac’s 2008 policy conference here.

On Monday, Senator John McCain, the presumptive Republican nominee for president, allied himself firmly with the Bush administration and charged that Mr. Obama’s calls for diplomacy with Iran were misguided and insufficient. And on Tuesday, Howard Friedman, Aipac’s president, used his introduction of Ms. Rice to implore her “to use your remaining time in office to ensure that Iran does not get a nuclear weapon.”

Mr. Obama, who is seeking the Democratic nomination, will have the opportunity to defend his position on Wednesday when he, along with Senator Hillary Rodham Clinton, his opponent, is scheduled to address the group.