Complex sentence: The other contenders were Morgan Godeau, Joe Sevario, and Carson K. Killen, of St. Amant in Ascension Parish, who had been an aide to Gillis Long and presumably Long's choice as his successor.
Split into simpler sentences: The other contenders were Morgan Godeau, Joe Sevario, and Carson K. Killen, of St. Amant in Ascension Parish. Killen had been an aide to Gillis Long and presumably Long's choice as his successor.