Britney Spears Was Wanted for the Film
Miramax Films distributed Chicago, and Harvey Weinstein, the now-disgraced and imprisoned movie mogul, was in charge at the time and often got his own way with the films he was involved in. For Chicago, he only had one name on his mind: Britney Spears. He wanted the young pop star to be given at least some kind of role in the film, ideally one of the two leads.
Weinstein allegedly sent three executives over to a Spears concert to chat with her about the idea, but director Rob Marshall and some of the producers were completely against the idea. They agreed that Spears was too young and naive to play a role that needed a serious and gritty side.