The pioneer spirit of this mountainous Western expanse was alive and well on Thursday, when Democrats gathered here for Barack Obama's acceptance of the nomination making him the first African-American presidential pick by a major US party. More than 70,000 party activists, journalists and local voters were arriving at Mile High Stadium Thursday evening to witness his acceptance speech making the case to the American public and the international community that he is the best person to lead the most powerful country in the world. He does so amid attacks from Republicans saying that the first-term senator from Illinois does not have the experience for the position, or the foreign policy credentials to steward the country in a time of conflict and peril. This is sure to be a major theme of the Republican effort to peel voters away from Obama, whose campaign used parts of this week's Democratic National Convention to counter such charges and to raise doubts about the wisdom of GOP policies in this arena. As the four-day convention reached its climax, presumptive Republican presidential nominee John McCain released two ads attacking Obama for his position on Iran and his inexperience dealing with global challenges. In one, a new television ad using mainly black and white images set to the ominous chiming of bells, the McCain campaign attacks Obama as "dangerously unprepared to be president" because he called Iran a "tiny" country that "doesn't pose a serious threat." As an image of an Israeli flag set before Jerusalem flashes across the screen, the narrator asks, "Terrorism? Destroying Israel? Those aren't serious threats?" An Associated Press analysis, however, faulted McCain for inaccuracy, since the comments had been taken selectively from a larger quote. "Strong countries and strong presidents talk to their adversaries," Obama said in May. "I mean, think about it. Iran, Cuba, Venezuela - these countries are tiny compared to the Soviet Union. They don't pose a serious threat to us the way the Soviet Union posed a threat to us. And yet we were willing to talk to the Soviet Union at the time when they were saying, 'We're going to wipe you off the planet.'" Obama campaign spokesman Hari Sevugan was quoted as saying, "John McCain is distorting Barack Obama's words to cover up for the fact that it's the failed Bush-McCain approach to foreign policy and the Bush-McCain war in Iraq that have strengthened Iran and endangered Israel." Delaware Sen. Joe Biden, in accepting the nomination for vice president Wednesday night, took a similar approach, lambasting McCain and President George W. Bush for "abysmal failures" in policies across the Middle East and charging that McCain was "wrong" when he rejected talking with Teheran. 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." A second Web short put out by the McCain campaign broadened the attack, accusing Obama of lacking the experience and judgment to be president, and using quotes from his erstwhile competitors for the Democratic presidential nomination making the same point. In one clip, taken from a debate during the primaries, Biden affirms a quote he made that "I think he can be ready to lead, but right now I don't think that he is. The presidency is not something that lends itself to on-the-job training." But Wednesday, in addition to attacking Republican foreign policies, the Democrats made the case that Obama was not only sufficiently prepared to lead, but to lead well. Former president Bill Clinton backed Obama during his speech and compared the candidate's background to his own. "We prevailed in a hard campaign in which Republicans said I was too young and too inexperienced to be commander-in-chief," he reminded the audience, referring to his own nomination 16 years ago. "My fellow Democrats, I say to you: Barack Obama is ready to lead America and to restore American leadership in the world," he declared. "Barack Obama is ready to be president of the United States."