An insider told 3AM Girls, "It's going to be a huge commitment for the girls, who are extremely devoted to their families. But they are overwhelmed by the world-wide response from their fans and don't want to let them down…The girls really want to do a huge tour but they're worried about how much time they'll be able to commit to it because of their families."

All of the five Spice Girls, but Melanie Chisholm and Emma Bunton, are mothers. And Bunton is pregnant and due in August. Says the source, "It's tricky for Victoria [Beckham] as she has three kids about to enroll in a new school and [Melanie Brown's] daughter Phoenix would struggle with the schedule, too, as she's also of school age. It's not going to be easy for Geri [Halliwell] and soon-to-be mum Emma traveling with their tots either. Mel C. has her solo career to consider, too, so they'll have to get her on board."

Still, it will be tough for the Girls to turn down the potential pay out for expanding the tour. They have currently signed up for 11 dates and 14 more are being finalized. For those, each Girl stands to make a total of about $20 million. Adding more dates would only make their wallets fuller.

The group is already showing signs that they may give in to the demand for more performances. On their website, they posted a message to fans announcing a contest in which the Girls will do a concert in the city with the most votes. That city will become Spice City.

An announcement about additional tour dates is expected any day now.