US Democratic convention: Crucial days for Obama
4 September 2012 Last updated at 22:49 BST
President Obama has promised to "finish what he's started" if he is re-elected to a second term later this year.
For his opponent, Mitt Romney, that win would take America backwards.
These are crucial days for Mr Obama's re-election bid, with the Democratic National Convention opening in North Carolina.
The BBC's North America Editor Mark Mardell sent this report.