The GOP/MSM have been holding back on sinking their knives into Cruz.
If for some reason Trump does drop out of the race, all of the fury of the GOPe/DNC/MSM will come down on Cruz like an avalanche of bricks.
They will literally try to crucify him in the court of public opinion.
Cruz is an easy target
None of his colleagues even like him or work with him
Persuading 52% of the electorate he is a loser won’t be difficult