Our first waves of entrance polling is giving us insight into who these caucus-goers are tonight.
On the Repbulican side, a third are over 65, and nearly 75 percent are over the age of 45. There are slightly more men than women, and more than 60 percent decided on their candidate more than a month ago. A third name Immigration their top issue, followed by the economy and terrorism.
The numbers also show a heavy turnout amongst evangelical Christians - over 60 percent.
–CNN Senior Political Analyst Schneider