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As President Obama takes the stage tonight to accept his party's nomination in Charlotte, he'll make his pitch as an embattled president in a virtually neck-and-neck race for a second term. Here's a look at Obama's evolution on the convention speech stage, from up-and-comer in 2004 to inspiring nominee in 2008 - and now, to a president arguing he needs more time to fix the economy and didn't betray his promise of change in his first term.

When he took the stage at the 2004 Democratic National Convention in Boston, Barack Obama was a first-time U.S. Senate candidate who was largely unknown outside his home state of Illinois. He delivered the keynote address on the second night of the convention, spellbinding attendees with a message of unity and spurring speculation of a potential presidential bid, himself:

"John Kerry believes in America. And he knows that it's not enough for just some of us to prosper. For alongside our famous individualism, there's another ingredient in the American saga: A belief that we're all connected as one people … It's what allows us to pursue our individual dreams, and yet still come together as one American family. E pluribus unum: Out of many, one."

"Tonight, there is not a liberal America, and a conservative America. There is the United States of America. There is not a black America and a white America and Latino America and Asian America. There's the United States of America … We are one people - all of us pledging allegiance to the stars and stripes. All of us defending the United States of America. In the end, in the end - in the end, that's what this election is about. Do we participate in the politics of cynicism, or do we participate in the politics of hope?"

Four years later, then Senator Obama took the convention spotlight once more, marching out into the roar of a jam-packed Invesco Field in Denver, to accept the Democratic Party's nomination. It was the first open-air stadium acceptance speech at a convention since John F. Kennedy in 1960, and as more than 84,000 attendees looked on, Obama energized them with his now-famous message of change.

"For 18 long months, you have stood up, one by one, and said "Enough" to the politics of the past. You understand that in this election, the greatest risk we can take is to try the same old politics with the same old players and expect a different result. You have shown what history teaches us : that at defining moments like this one, the change we need doesn't come from Washington. Change comes to Washington."

"Change happens because the American people demand it - because they rise up and insist on new ideas and new leadership, a new politics for a new time. America, this is one of those moments. I believe that as hard as it will be, the change we need is coming."