News that director Ron Howard was making movies of the novels sparked a casting frenzy with major actors desperate for what could easily be a career-defining role.
Javier Bardem and Viggo Mortensen were both tipped to play the main character, gunslinger Roland Deschain - but now insiders say Bale is the favorite to lead what promises to be a blockbuster franchise.
Bale has won a slew of awards as Best Supporting Actor for his part in The Fighter, and is a clear favourite for the Oscar.
A source said Dexter star Jennifer Carpenter is rising on the short list for the role of Susannah, as is French-Moroccan actress Ghita Tazi.