I guess that is why Cruz has now started taking on Rubio. It looks more like Cruz has decided that he better battle Rubio for 2nd place.
He could also be trying to grab the anyone but Trump vote.
Given that the majority of people view Trump negatively (I had read in one article that it is in the 60% range), most people don’t want him. Perhaps things will change as the field clears out, but Trump does not (cannot) win the nomination outright if most people vote for someone else besides him.