Ted Cruz has played the race so perfectly right now that he has the highest favorability of any candidate in the race.
Back in 2015, when Trump had the highest popularity, he could savage all comers and crush them. People loved it. They liked him. But Cruz’s likability has steadily risen and he is now the most liked candidate.
In South Carolina, when Trump started attacking Cruz from the stage, the crowd booed him. In fact, the booing got louder the more Trump attacked.
When Cruz got on stage, he ignored Trump altogether. He did not have to say anything. The crowd did it for it.