Complex sentence: Robert called Pierre Salinger and Kenneth O'Donnell to assist him; realizing the ramifications of counting Texas votes as their own, Salinger asked him whether he was considering a Kennedy-Johnson ticket, and Robert replied "yes".
Split into simpler sentences: Robert called Pierre Salinger and Kenneth O'Donnell to assist him. Realizing the ramifications of counting Texas votes as their own, Salinger asked him whether he was considering a Kennedy-Johnson ticket, and Robert replied "yes".