DES MOINES, Iowa – Barack Obama's presidential campaign says Olympic gymnast Shawn Johnson will lead the Pledge of Allegiance at the Democratic National Convention on Thursday.

Obama is expected to give his acceptance speech Thursday night at Invesco Field at Mile High stadium in Denver.

The 16-year-old Johnson won four medals at the recent Olympics in Beijing, including a gold in the women's balance beam competition.

She begins a 40-city gymnastics tour next week.