Delivering his first public address since claiming victory in his quest for the Democratic presidential nomination, Barack Obama tried to make the case on Wednesday that no one should question his support for Israel and argued that he was the best candidate when it came to the Jewish state's security.To sustained applause and half a dozen standing ovations - the strongest reception given to any of the dignitaries who addressed the American Israel Public Affairs Committee's three-day conference, including his Democratic competitor Hillary Clinton and the presumptive Republican nominee John McCain - Obama stressed his ties to the Jewish community, the importance of a secure Israel and his vow that he would "do everything in my power to stop Iran from obtaining nuclear weapons."Watch address:He staked out some hawkish positions, declaring that "Jerusalem will remain the capital of Israel, and it must remain undivided," and termed Israel's attack in September on Syria's alleged incipient nuclear facility "entirely justified to end that threat."Obama also took on the e-mail campaign that has circulated through the Jewish community, which highlights his middle name - Hussein - as part of accusations that he's a secret jihadi, and other spurious claims."All I want to say is, let me know if you see this guy named Barack Obama, because he sounds pretty scary," he said to laughter.Though he made light of the subject, the e-mail campaign and other similar rumors, as well as his ties to controversial figures such as his former preacher, Rev. Jeremiah Wright, have contributed to concerns about his stance on Israel and the Middle East in some segments of the Jewish community. He has also engendered skepticism from some pro-Israel voters because of his stated willingness to talk to the leaders of Iran and other more dovish positions.In Wednesday's speech, Obama continued to call for early, sustained American engagement in the peace process for a two-state solution - with an end to new settlements - and an emphasis on diplomacy when it came to Iran, but he put a more assertive face on his policies.Implying that his position on meeting with the leaders of enemy countries had been mischaracterized, Obama stressed, "I would be willing to lead tough and principled diplomacy with the appropriate Iranian leaders at a time and place of my choosing, if and only if it can advance the interests of the United States.""Let there be no doubt: I will always keep the threat of military action on the table to defend our security and our ally, Israel," he said.His comments weren't enough to satisfy the McCain campaign, which accused him of massaging his position on key issues of concern to the Jewish community. Sen. Joseph Lieberman (I-Connecticut) described a "disconnect" between Obama's words on Iran Wednesday and earlier statements in a conference call with the media following the Illinois senator's speech.Lieberman is widely popular with the AIPAC crowd and is a key component of McCain's efforts to peel Jewish voters away from the Democratic party, traditionally a stronghold of Jewish support. With Clinton, an early favorite of the Jewish community, all but out of the race and Obama perceived as being vulnerable on Israel in some quarters, the McCain camp hopes to use its candidate's lengthy experience with national security issues and record of support for Israel to win over Jews.Obama made a bid for bipartisanship on Israel, when he made his speech's one cross-aisle reach to say - referring to a commitment to Israel's security - that "that is a commitment that both John McCain and I share, because support for Israel in this country goes beyond party."In response, McCain senior foreign policy adviser Randy Scheunemann said that Obama was right that support for Israel has been bipartisan, but he wasn't willing to give the senator a pass on the issue. Instead, he argued that Obama's positions "would undermine Israel's security," referring to a "naÃ¯ve" approach of withdrawal from Iraq that he charged would embolden Iran and al-Qaida.Obama also used the Iraq issue to pummel his opponent, arguing that McCain's "failed" Iraq policies had strengthened Iran and endangered Israel.Obama got help in making his case from an unlikely quarter when Hillary Clinton addressed the AIPAC conference after her rival.Clinton, who enjoyed an equally warm but less enthusiastic reception, told the audience to applause, "Let me be very clear: I know that Senator Obama will be a good friend to Israel."Despite the at-times bitter race between them, Clinton, fresh off of a speech promising party unity following the last primaries on Tuesday night, demonstrated a willingness to support the Democratic candidate with her remarks on his Israel record, which had been one of the key advantages she had tried to exploit in their competition."I know that Senator Obama shares my view that the next president must be ready to say to the world: America's position is unchanging, our resolve unyielding, our stance nonnegotiable," she said. "The United States stands with Israel, now and forever."