If he doesn't win; its all over for him. You can't be the schoolyard bully he has been with a black eye.
Bah. He's the underdog in Iowa. If Trump wins, or Cruz only wins by a little...it's over for Cruz.
But, if Trumps wins Iowa...it's all but over.
After Iowa, Trump wins New Hampshire hands down.
Then Trump wins South Carolina.
I don't think any Republicans have lost the nomination after winning those three...