US Democrats prepare for pre-election convention

The three-day Democratic National Convention is set to open - formally re-nominating Barack Obama and Joe Biden as the party's presidential and vice-presidential candidates.

First Lady Michelle Obama will give a keynote speech on the opening day of the convention in Charlotte, North Carolina.

The event - like the Republican National Convention in Florida last week - has been hit by poor weather.

The BBC's Steve Kingstone reports from Charlotte.