Complex sentence: After the necessary signatures had been certified, death penalty opponents filed a lawsuit to cancel the referendum, arguing that Governor Ricketts should have been registered has a petition "sponsor" because he was "in actuality the primary initiating force".
Split into simpler sentences: After the necessary signatures had been certified, death penalty opponents filed a lawsuit to cancel the referendum. They argued that governor Ricketts should have been registered has a petition "sponsor" because he was "in actuality the primary initiating force".