battled all the way down to the wire was 1976, a floor fight is maybe the only way for the party to negotiate itself out of a trump nomination. but now it's no longer just the businessman threatening to abandon the party. cnn's senior washington correspondent jeff zeleny is in des moines, iowa. jeff, dr. ben carson has now made a similar threat that he may jump ship adds well? >> he has, jim. this big tent of the republican party is facing a big test just 52 days before the iowa caucuses. but as gop leaders fret about donald trump becoming the nominee, senator ted cruz is doing some not so secret maneuvering to be in position if trump falls. tri trump, still comfortably on top of the republican field, has a new rival nipping at his heels. for the first time, ted cruz signalled his plan at a closed-door fund-raiser to take on trump and ben carson.