Newly minted Democratic presidential nominee Barack Obama pledged tough diplomacy on Iran, and spoke of the need to protect Israel as he accepted his party's nomination before more than 70,000 cheering supporters in Denver Thursday night. Amidst a frenzy of waving flags and wild applause, Obama became the first African-American presidential nominee of a major party. He accepted the role at the largest ever nomination event, capped by fireworks, chants of his signature slogan, "Yes we can!," and thousands of hand-held placards simply saying, "Change." Obama detailed a long list of the policies that would constitute that change, including a pledge to end America's dependence on Middle East oil within ten years. Criticizing presumptive Republican presidential nominee John McCain's foreign policy approach by saying that "you don't protect Israel and deter Iran just by talking tough in Washington." Further, he said that he would "renew the tough diplomacy that can prevent Iran from acquiring nuclear weapons." He also called for a withdrawal of American troops from Iraq, and a greater effort against al-Qaida and the Taliban in Afghanistan. Obama pushed back against attacks that he's not ready to lead and lacks foreign policy experience, as the Republicans have charged. He declared, "If John McCain wants to have a debate about who has the temperament and the judgment to be the next commander and chief, that's a debate I'm ready to have." Obama delivered his 44-minute speech in a dramatic setting, a filled sports stadium, the camera flashes in the night, the made-for-television backdrop that suggested the White House, and the thousands of convention delegates seated around the podium in an enormous semicircle. "We meet at one of those defining moments, a moment when our nation is at war, our economy is in turmoil, and the American promise has been threatened once more," Obama said. "America, we are better than these last eight years. We are a better country than this," he said. Obama's speech came one day after Democrats made him the first black presidential nominee of a major US political party. His address coincided with the 45th anniversary of one of the most critical events in the American civil rights movement: Martin Luther King Jr.'s "I Have a Dream" speech. Obama mentioned but did not dwell on the anniversary. His campaign has tried to prevent his candidacy from being defined by his race as it tries to appeal to a wide swath of the American electorate. He did not mention his own race, although he noted, "I realize that I am not the likeliest candidate for this office. I don't fit the typical pedigree." A Gallup poll taken during the first three days of the convention showed Obama regaining his lead over McCain, 48 percent to 42 percent. Candidates generally receive a bounce from their conventions, and the figures could tilt in McCain's direction after Republicans hold their convention in St. Paul, Minnesota, next week. Obama said he wanted to give his acceptance speech at a large sports stadium so many supporters, not just party insiders attending the convention, could attend. Several celebrities performed, including singers Sheryl Crow, Stevie Wonder and will.i.am. In a novel bid to extend the convention's reach, Obama's campaign decided to turn tens of thousands of partisans in the stands into instant political organizers. They were encouraged to use their cell phones to send text messages to friends as well as to call thousands of unregistered voters from lists developed by the campaign. Republicans were quick to deride the stage setting as one that befitted an unaccomplished celebrity, a theme they used when Obama drew tens of thousands for an appearance in Berlin.