NEW YORK TIMES: Polls show a close race for both parties.
Hillary Clinton is leading Bernie Sanders by around three percentage points, and Donald Trump is ahead of Ted Cruz by a more comfortable eight-point margin. Marco Rubio holds a strong third place in the Republican race at around 15 percent.
But polling, of course, is not perfect. It’s more challenging in primaries than in general elections, where there are far fewer undecided voters and where turnout is more predictable. These challenges are even greater in an early caucus; the turnout is especially variable and the views of voters are unsettled between many more candidates than remain in later states.