Donald Trump was the clear favorite in today’s winner-take-all Arizona primary, even before the Brussels terrorist attacks. The immigration issue and the flood of early voters favors him, as does the fact that some of those early voters will have cast ballots for Marco Rubio before he dropped out last Tuesday night. If they had known Rubio would no longer be a candidate, many of those voters might have gone with Cruz. But polls have been tricky and often erratic this year (think Michigan and the surprise win of Bernie Sanders). For example, the latest poll showing a 14 point...