Dan Balz describes the resilience of Donald Trump's candidacy, and the contest between Cruz and Trump, both tapping into anger at the grassroots. He points to the little headway made by the other candidates, Rubio, Kasich, Bush and Carson. Trump's high moment was when he described the way New Yorkers handled the 9/11 collapse of the World Trade Center and other buildings. Cruz passionately handled questions on the birth issue- being born of an American mother in Canada- and the loan from Goldman Sachs, coming out stronger than before.