As the field narrowed, Cruz's position in the race strengthened, owing to his debate performances and strong field infrastructure. He won the Iowa Caucuses in February, the first contest of the race. But as the field narrowed and less-viable candidates dropped out, Republican support concentrated around Trump rather than Cruz. Trump beat Cruz handily on Super Tuesday and in most subsequent primaries. At this point, with the race essentially narrowed to one between Cruz and Trump, the two candidates began to openly criticize each other (whereas they had previously been notably cordial). Trump repeatedly called Cruz "Lyin' Ted" and on one occasion retweeted a deprecating tweet regarding the physical appearance of Cruz's wife. Trump also parroted a story in the "National Enquirer" claiming that Cruz's father, Rafael Cruz, was involved in the Assassination of President John F. Kennedy. Cruz called Trump a chronic liar, "completely amoral", and questioned whether he was a genuine conservative.