The first-in-the-nation presidential caucus has arrived after months and months of campaigning. Republican presidential candidates spent their final weekend in Iowa urging supporters to brave brutally cold temperatures to vote in today’s first nominating contest. The icy weather is raising questions about voter turnout, even in a Midwestern state accustomed to harsh winters. Donald Trump heads into the evening caucuses with a 28-point lead over Nikki Haley, according to the Des Moines Register/NBC News Iowa Poll.