Complex sentence: Presley's role had originally been turned down by both Jeffrey Hunter and Robert Wagner because the part was too small, but when Presley signed up to the picture the role was expanded to take advantage of his current popularity.
Split into simpler sentences: Presley's role had originally been turned down by both Jeffrey Hunter and Robert Wagner because the part was too small. When Presley signed up to the picture the role was expanded to take advantage of his current popularity.