CHARLOTTE, N.C. -- With his trademark soaring rhetoric, President Obama promised Thursday night to "honor the strivers, the dreamers, the risk-takers who have always been the driving force behind our free enterprise system."

He said the path "won't be quick or easy ... it will take more than a few years for us to solve challenges that have built up over decades."

The presidential election poses a stark choice, he said. "We can give more tax breaks to corporations that ship jobs overseas, or we can start rewarding companies that open new plants and train new workers. We can create a million new manufacturing jobs in the next four years."

(Watch highlights from Obama's speech above, or view his full remarks below)

Obama's speech before a crowd of 20,000 had a much different tone than the one he delivered in 2008 when he accepted the nomination in Denver before a packed Invesco Field at Mile High Stadium. This time, the venue was changed Wednesday from Bank of America Stadium to the convention hall because of concerns about the weather.

While hope and change were the dominating themes four years ago, Obama used much of this address to defend his first term in office and attack his opponent, Republican presidential nominee Mitt Romney. He also distinguished his vision for the future from what he believes the Republican Party has in store for America, which he said would end up "wrecking the middle class."

(Read the full text of Obama's speech)

The Republican way of moving the nation forward, Obama said, leaves out the most vulnerable.

"That's not who we are," Obama said. "That's not who this country is about."

"I want to reform the tax code so that it's simple, fair, and asks the wealthiest households to pay higher taxes on incomes over $250,000 -- the same rate we had when Bill Clinton was president ... 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 cut."

He promised to "reform and strengthen Medicare" over time. "But we'll do it by reducing the cost of health care -- not by asking seniors to pay thousands of dollars more."

He went out of his way to tout his national security credentials: "Four years ago, I promised to end the war in Iraq. We did. I promised to refocus on the terrorists who actually attacked us on 9/11. We have. We've blunted the Taliban's momentum in Afghanistan, and in 2014, our longest war will be over. A new tower rises above the New York skyline, al Qaeda is on the path to defeat, and Osama bin Laden is dead."

He said Romney and his running mate, Paul Ryan, "want to take us back to an era of blustering and blundering that cost America so dearly ... After all, you don't call Russia our number one enemy -- and not al Qaeda -- unless you're still stuck in a Cold War time warp."

"And while my opponent would spend more money on military hardware that our Joint Chiefs don't even want, I'll use the money we're no longer spending on war to pay down our debt and put more people back to work ... After two wars that have cost us thousands of lives and over a trillion dollars, it's time to do some nation-building right here at home."

Obama also told the crowd he is now "far more mindful of his own failings," and quoted Lincoln, who said, "I have been driven to my knees many times by the overwhelming conviction that I had no place else to go."

The man who campaigned on the theme of "hope and change" last time around now said he took strength from the American people.

"If you buy into the cynicism that the change we fought for isn't possible ... well, change will not happen," he said. "I'm hopeful because of you."