Donald Trump and Texas Sen. Ted Cruz are circling each other in the race for the Republican nomination and appear to be on the brink of an epic clash. While the candidates have for months observed a kind of truce, party insiders believe that's about to change - and many are speculating about just how explosive things will get. Trump appears to be feeling the heat from Cruz, who now enjoys a small but significant polling lead in Iowa, which will hold the first nominating contest on Feb. 1. In recent days, he has begun to jab Cruz in more...