If I were a politician,there is nobody I would fear calling me out more than Cruz.
I could well be wrong,but I honestly think he is the smartest man in US politics,and while it seems to take a lot to get him worked up,once he is,he is relentless.
He is even smart enough to only mention proven truths or truths that can be easily proven if challenged,and this is what probably makes him so feared by the other pols.
It's really hard to fight back against someone who is only telling the truth,and who can prove it if challenged.