Democrats formally named Barack Obama and Joseph Biden as their respective presidential and vice presidential candidates Wednesday, hoping to end eight years of Republican control of the White House. Former Obama rival Hillary Rodham Clinton interrupted a state-by-state roll call vote at the Democratic National Convention to ask delegates to make Obama's selection unanimous "in the spirit of unity, with the goal of victory." They agreed, with a roar. Later at the convention, Senator Biden of Delaware, in accepting the Democratic nomination, attacked Republican presidential candidate John McCain's policy choices and argued that he and Obama would better protect America. "As we gather here tonight, our country is less secure and more isolated than in any time in recent history. The Bush-McCain foreign policy has dug us into a very deep hole with very few friends to help us climb out," he declared. Biden described their policies in Russia, Iraq, Pakistan and Afghanistan as "a abysmal failure," before turning to Iran. He pointed to Obama's call for more engagement with Iran, saying, "Now, after seven years of denial, even the Bush Administration recognizes that we should talk to Iran, because that is the best way to ensure our security." Biden charged that McCain was "wrong" when he rejected talking with Teheran. He also praised Obama's judgment that the US should shift responsibility to the Iraqi government and set a time to bring US combat troops home. Biden said he learned the quality of Obama's character while campaigning against him for the presidential nomination. "I watched how Barack touched people, how he inspired them, and I realized he had tapped into the oldest American belief of all: We don't have to accept a situation we cannot bear. We have the power to change it," he said. Biden was greeted with warm and sustained applause by the audience of Democratic delegates and activists and was joined by his extended family and surprise guest Obama on stage at the conclusion of his speech. Obama told roaring delegates that he wanted people to understand why he was proud to have "the whole Biden family on this journey with me to take America back." He deadpanned at one point that he thought the convention had "gone pretty well so far." The Democratic presidential nominee also praised his wife, his former rival and former president Bill Clinton for going to bat for him. "I think Michelle Obama kicked it off pretty well, don't you think?" he said, as the crowd roared, adding, "If I'm not mistaken, Hillary Clinton rocked the house down last night!" He also praised former US president Bill Clinton, who spoke earlier Wednesday night, as someone who reminds us about "what it's like when you've got a president who actually puts people first. Thank you President Clinton." Obama's formal acceptance speech Thursday night was expected to draw a crowd of 75,000 at a nearby outdoor stadium. Bill Clinton, whose past support for Obama has been tepid, had told delegates and a national television audience that Obama "is ready to lead America and restore American leadership in the world." Noting that his wife had told the convention that she would do everything possible to get Obama elected, he said: "That makes two of us." For months, the former president had made little secret of his disappointment over his wife's primary defeat. During her campaign, he faced criticism for his outbursts of anger and deprecatory comments about Obama. But his 1993-2001 presidency is warmly remembered by Democrats as a time of peace and prosperity. He was greeted with a long, huge ovation and interrupted with applause as he lauded Obama. "Everything I've learned in my eight years as president and the work I've done since, in America and across the globe, has convinced me that Barack Obama is the man for this job," he said. Less than an hour before the roll call, Hillary Clinton began an emotional gathering with her delegates by telling them she had released them to vote for Barack Obama. Many in the crowded ballroom yelled back "No!" Despite releasing her delegates, Clinton received 341 votes - to Obama's 1,549 - before she called for him to be approved by acclamation. Obama has campaigned on a theme of hope and change, tapping into voter dissatisfaction with the old politics of Washington and the unpopular presidency of Republican George W. Bush. He was little known outside his home state of Illinois until 2004 when, as a candidate for the Senate, he dazzled with a keynote address at the Democratic National Convention. He won election to the Senate, then announced his presidential candidacy a scant two years after arriving in Washington. With his gifts as a speaker, his astounding ability to raise money on the Internet and an unmatched ground operation pieced together by political veterans, he won a stunning victory in the first nominating contest, the Iowa caucuses on Jan. 3. Obama has pledged to pull US combat forces out of Iraq in 16 months and to make health care available to all Americans. He has called for bipartisan unity and targeted western and southern states that have been Republican strongholds. But he is vulnerable in northern industrial states, Clinton strongholds that have been crucial to Democratic hopes. Obama, his wife, Michelle, and Biden and his wife, Jill, will embark on a bus tour of three of those states: Pennsylvania, Ohio and Michigan. Republicans hold their convention next week to anoint McCain as their candidate. He has not yet announced a running mate, but was expected to do so soon. On Wednesday, McCain's campaign released a new TV ad saying that Obama showed he was "dangerously unprepared" for the White House when he described Iran as a "tiny" nation that did not pose a serious threat. Missing from the ad was the context of Obama's remarks last May in which he compared Iran and other US adversaries to the superpower Soviet Union. In his speech, Bill Clinton defended Obama's national security credentials. Recalling that when he ran for president at age 46 in 1992, "Republicans said I was too young and too inexperienced to be president." "Sound familiar?" Clinton said. "It didn't work in 1992, because we were on the right side of history. And it won't work in 2008, because Barack Obama is on the right side of history."