In a nationally televised speech in which he accepted the Democratic presidential nomination, Obama pressed the themes that will guide his campaign through the November 4 election: that he will help the country's struggling middle class and be strong on national security, and that a victory for rival John McCain would amount to a third term for Bush.
"Tonight, I say to the people of America, to Democrats and Republicans and independents across this great land - enough!" he said.
The speech capped the four-day Democratic National Convention, where he sought to unite a party divided after a bitter primary fight and regain momentum in the campaign against McCain.
In an audacious move, McCain sought to steal some of the political spotlight by spreading word that he had settled on a vice presidential running mate. Minnesota Gov. Tim Pawlenty canceled all scheduled appearances for the next two days, stoking speculation that he was the one.
Obama's speech was delivered in a dramatic setting, a filled sports stadium, the camera flashes in the night, the made-for-television backdrop that suggested the White House, and the thousands of convention delegates seated around the podium in an enormous semicircle.
"We meet at one of those defining moments, a moment when our nation is at war, our economy is in turmoil, and the American promise has been threatened once more," Obama said.
"America, we are better than these last eight years. We are a better country than this," he said.
Obama's speech came one day after Democrats made him the first black presidential nominee of a major U.S. political party. His address coincided with the 45th anniversary of one of the most critical events in the American civil rights movement: Martin Luther King Jr.'s "I Have a Dream" speech.
Obama mentioned but did not dwell on the anniversary. His campaign has tried to prevent his candidacy from being defined by his race as it tries to appeal to a wide swath of the American electorate.
