© The Associated Press
US, Washington - President Barack Obama addressed the largest pro-Israel policy conference Sunday morning in a speech that offered tough words for Iran but an even stronger defense of his administration's own policies toward Israel.

"If during this political season you hear some question of my administration's support for Israel, remember that it's not backed up by the facts," Obama said in his speech at the American Israel Public Affairs Committee (AIPAC). "There should not be a shred of doubt right now: When the chips are down, I have Israel's back."

As the specter of a nuclear-armed Iran loomed over the three-day conference, Obama reaffirmed his willingness to use "all elements of American power" -- including military force -- to prevent Iran from obtaining a nuclear weapon, and denounced a policy of containment.

Obama will meet on Monday with Israeli Prime Minister Benjamin Netanyahu at the White House, where the two are expected to vigorously debate Israeli's concern that the U.S. has not done enough to prevent Iran for acquiring a nuclear weapon.

But in his speech, Obama also defended his administration's approach of sanctions and diplomacy, saying that he would rather see diplomatic solutions prevail than military ones, and that he has "a deeply-held preference for peace over war."

"Already there is too much loose talk of war," Obama said. "Over the last few weeks, such talk has only benefited the Iranian government, by driving up the price of oil, which they depend upon to fund their nuclear program. For the sake of Israel's security, America's security, and the peace and security of the world, now is not the time for bluster; now is the time to let our increased pressure sink in, and to sustain the broad international coalition that we have built."

A broader challenge facing Obama at the AIPAC conference, and heading into a heated election season, was the increasingly suspicious pro-Israel community.

By the time Obama spoke at the conference, a session-opening foreign policy roundtable had injected a mood of partisan rancor into the proceedings, with Liz Cheney, a former State Department official, and daughter of Vice President Dick Cheney, telling the audience that she hoped that next year's AIPAC forum would take place under a different administration.

"There is no president who has done more to delegitimize and undermine the State of Israel than President Obama," Cheney said, to huge applause from the expected 13,000 attendees at the Washington Convention Center.

The audience cheered slightly louder when Jane Harmon, the director of the Woodrow Wilson Center and former Democratic congresswoman from California, responded that Israel must not become a "political football."

Running off a litany of examples of how his administration had backed Israel's interests in the past few years -- from the highest level of security aid ever to his staunch objections to Palestinian attempts to seek statehood at the United Nations last year -- Obama declared, ""As you examine my commitment, you don't just have to count on my words, you can look at my deeds."

"In the end support for Israel is bipartisan and that is how it should stay," Obama said.