carolina, where the 2012 democratic convention has entered the history books with a speech by president barack obama. A stirring speech for the people here in the hall. He launched a vigorous defense... See More
carolina, where the 2012 democratic convention has entered the history books with a speech by president barack obama. A stirring speech for the people here in the hall. He launched a vigorous defense of his record, several negative attacks against mitt romney and he offered the delegates a little bit of that old-time obama religion of hope. All in all, the people who were in this hall, received this speech, they were elek triified by it. They were explosive at times. You could hear them yearning for his success. The real question is, how does this play outside the hall, in the un country, with you? Because the president has significant challenges ahead of him. ♪ they still love him. Barack obama may be struggling in the polls and fighting for his political life, but tonight among the democrats gathered here, any doubts or disappointment seemed to disappear. Madam chairwoman, delegates, I accept your nomination for president of the united states. Reporter: Still, you couldn't help but think what a difference four years have made. He's so much grayer now, the toll the presidency takes, that youthful aura that still clung to barack obama in 2008, has been burned away by the searing pressures of power. So he spoke tonight as a man of hard and sometimes bitter experience, of survival. I recognize that times have changed since I first spoke to this convention. Times have changed and so have i. I'm no longer just a candidate. I'm the president. Reporter: This was a political party that will need every once of effort to re-elect president obama. That's why you saw former congresswoman gabby giffords unite this hall in tears and cheers as she recite the pledge of allegiance. Reporter: And that's why vice president joe biden went all out too. We can now proudly say what you've heard me say the last six months. Osama bin laden is dead and general motors is alive. Reporter: The president did something else. He addressed directly the frustrated hopes and mixed feelings about his leadership out across the country. Now, I won't pretend the path I'm offering is quick or easy. I never have. You didn't elect me to tell you what you wanted to hear. You elected me to tell you the truth. and the truth is, it will take more than a few years for us to solve challenges that have built up over decades. Reporter: Truth and struggle. ♪ Reporter: A long way, perhaps, from the euphoria of hope and change. This was really the presiden biggest challenge tonight, the biggest challenge in his campaign, to overcome the disappointments and the doubts among so many americans who voted for him in 2008. And give them home again. I think they're looking for the combination of that vision, the hope that he offered in '08, but the reality of just how we're going to do it. Reporter: We chatted with the author of the definitive biography of obama so far. What happened with the 2008 voters who were so full of hope? What happened to the hope? I think in one sense, obama went into office thinking that he could somehow transform this place. But he didn't really have the experience in washington to understand what it would take to try to bring things together. Reporter: Somewhere it seemed obama stopped driving eventsnd seemed more driven bipartisan cyclones and fierce economic head winds. But that's not supposed to happen to strong presidents. A republican ad mocked his efforts to explain. Barack obama's got lots of excuses for the bad economy. Head winds coming from europe. We've had a string of bad luck. An earthquake in japan. Reporter: And in 2008, he promised so much more. This was the moment when the rise of the oceans began to slow and our planet began to heal. Rolling back the bush tax cuts on the top 1 percent. As we took a stroll tough the delegations today, we heard democrats fire back in the president's defense. Everyone did expect hope and change and they expected it instantaneously. However, the mess of created over a lengthy period of time. It's a partisan fight to death, this campaign. So obama went negative, early and often, unusually for an incumbent president. When governor romney and his friends in congress tell us we can lower our deficits by spending trillions more on new tax breaks for the wealthy, what did bill clinton call it? You do the arithmetic. I refuse to ask middle-class families to give up their deductions for owning a home or raising their kids just to pay for another millionaire's tax cuts. Reporter: In the end, it was, once again, that barack obama spoke of. Hope in tough times. America, I never said this journey would be easy, and i won't promise that now. Yes, our path is harder, but it leads to a better place. Yes, our road is longer, but we travel it together. We don't turn back. We leave no one behind. We pull each other up.
This transcript has been automatically generated and may not be 100% accurate.