Michelle kicks off Obama campaign

US Democrats have launched president Barack Obama on his uncertain bid for re-election as they opened their national convention.

They looked to help Mr Obama recapture the hearts of Americans once drawn to his message of hope and change, but now weary after years of economic weakness and political squabbles.

The nationally televised, three-day convention puts Democrats in the spotlight, allowing them to depict Mr Obama as a courageous, compassionate leader who has put the United States on the right track after inheriting a brutal recession.

They countered attacks made at last week's Republican convention and cast rival Mitt Romney, a wealthy businessman and former Massachusetts governor, as distant, privileged and out of touch with ordinary Americans.

The star speaker, first lady Michelle Obama, drew a contrast between her husband and Mr Romney without mentioning the Republican's name.

She talked about her husband's more humble background as a young man who drove a rusty car and wore dress shoes that were a size too small.

She painted a portrait of a leader who knows first-hand the struggles of everyday Americans, who listens to them as president, and who pushes an agenda with their interests in mind.

"That's the man I see in those quiet moments late at night, hunched over his desk, poring over the letters people have sent him," she said. "I see the concern in his eyes ... and I hear the determination in his voice as he tells me, 'You won't believe what these folks are going through, Michelle. it's not right. We've got to keep working to fix this. We've got so much more to do'."

Polls show Mr Obama and Mr Romney locked in a tight race ahead of the November vote. Mr Romney is seen as the better candidate for improving the economy, the biggest issue in the race. But Mr Obama is seen as more likeable and better able to connect with the concerns of middle-class Americans.

Other convention highlights include the roll call votes formally nominating Mr Obama and vice president Joe Biden, and a speech by Bill Clinton, the popular former president. The climax will be Mr Obama's acceptance speech at a 74,000-seat American football stadium.