BOCA RATON, Fla. — Beginning a courtship likely to last until November, Senator Obama came to a large synagogue here with a clear message of support for Israel and a plea to the Jews of Florida: Ignore the rumors and judge me by what I say and do.

RELATED: Obama and Israel – A New York Sun Special.

Mr. Obama made his most direct appeal to one of Florida’s crucial Democratic constituencies yesterday, facing many voters curious about his background and skeptical about his candidacy.

The Illinois senator and likely Democratic nominee pledged an “unshakable” commitment to Israel, saying he would work to maintain the security of the Jewish state as well as to “make every effort” to help it forge a lasting peace with its neighbors in the Middle East.

“Israel has many friendships, but none is deeper than the bond between Israel and the United States of America,” Mr. Obama said, drawing applause from a packed auditorium at the B’nai Torah Congregation in Boca Raton. “A broad majority of Americans understand this special relationship, and when I am in the White House, I will bring an unshakable commitment to maintaining that bond.”

While Mr. Obama explained and defended his proposal for direct engagement with Iran, he said its rhetoric toward Israel was “unacceptable” and pointedly avoided language that would minimize the danger it poses. He has faced criticism from the presumptive Republican nominee, Senator McCain, for calling the threat of Iran and other enemies “tiny” compared to that posed by the Soviet Union during the Cold War.

“The greatest threat to Israel today obviously comes from Iran,” Mr. Obama said yesterday. “The threat of Iran is real and it is great, and my goal as president will be to eliminate it.”

For Mr. Obama, the goal yesterday was to connect with a group of voters who are relatively unfamiliar with him even after 16 months on the stump. Mr. Obama did not campaign in Florida in the months leading up to its disputed January primary, and his opponents, Senators McCain and Clinton, have long been known as allies of Israel.

After breezing through opening remarks, Mr. Obama took questions, light-heartedly assuring the audience that they were not “pre-screened” and even suggesting they save the softballs. “I like the tough ones,” he quipped.

A few members of the crowd responded in kind; one man asked about Mr. Obama’s name, saying he had sensed among some people an attitude that said, “If Barack Obama would change his name to Barry, I would vote for him.”

Mr. Obama took the question in stride, telling the man that although he went by “Barry” as a child, he had later switched to Barack, a name he shared with his Kenyan father. He noted that “Barack” shares a meaning with the Hebrew word “baruch,” or blessed.

Another questioner, Michael Ackerman, began his query by citing a list of people linked to Mr. Obama who had been hostile to Israel, including a professor of Arab studies at Columbia University, Rashid Khalidi. After the crowd began to boo, Mr. Ackerman asked Mr. Obama to name American Jews who were “close, personal friends.”

Mr. Obama hesitated, saying it made recall the old stereotype in which people say, “I’m not prejudiced. Some of my best friends are Jewish.”

He cited a top finance official in his campaign, Penny Pritzker, along with an executive board member of the American Israel Public Affairs Committee, Lee Rosenberg.

He acknowledged knowing Mr. Khalidi and called him “a respected scholar,” but he said they “vehemently” disagree on Israel policy. “He is not one of my advisers. He is not one of my foreign policy people,” Mr. Obama said.

The senator drew a loud ovation when he urged the crowd against judging him by his ties to figures who have made contentious or anti-Semitic statements. “We have to be careful about guilt by association,” he said.

At the same time, Mr. Obama sought aggressively to dispel doubts that have percolated among some voters. “If you get one of those e-mails that says I’m a Muslim: Not true. Never been a Muslim,” he said. “Don’t judge me by my name,” he added.

Unprompted, he distanced himself from President Carter, saying he strongly disagreed with the former leader’s advocacy of direct talks with Hamas. And before concluding the event, he addressed fliers he said were handed out by Republicans that raised questions about his stance on Israel, even though no one in the audience had asked about them.

The crowd responded warmly to Mr. Obama, giving him a standing ovation at the conclusion of the two-hour town hall meeting. Several audience members, particularly senior citizens, said they had been uneasy about the senator but came away impressed. “I was not a fan of Obama,” George Braverman, 84, said. “I was very pleasantly surprised by what I heard.”

Still, Mr. Braverman, a lifelong Democrat, said he was unsure if he would vote for Mr. Obama or Mr. McCain in the fall.

David Felder, 84, of Delray Beach, said he had “qualms” about Mr. Obama being a Muslim, but that the senator had erased them.

One topic that drew little attention yesterday was Mr. Obama’s Democratic opponent, Senator Clinton, or her ongoing battle to have the delegation from Florida seated according to her victory in the January election, which was sanctioned by the Democratic National Committee. The Clinton campaign held a conference call with reporters to push the issue, but Mr. Obama made no mention of it during his remarks, and he was not asked about it by the audience.