Exit polls across New Hampshire today will offer a broad look at how primary voters made their decision. Here are five key factors to watch in tonight’s results. Tonight, we’ll be producing up to the minute exit poll results and analysis on the Behind the Numbers blog and @postpolls on Twitter.

Ron Paul (Associated Press)

Among voters who said they would definitely vote, Paul earned 15 percent in the final University of New Hampshire poll. He earned 28 percent, though, among those who plan to vote “unless some emergency comes up.” No other candidate sees such a discrepancy between these groups.

2. Undeclared voters — Ron Paul and Jon Huntsman’s prospects may hinge on voters who aren’t registered with the Republican Party, but who are allowed to vote in Tuesday’s primary. In 2008, they made up nearly four in 10 voters. This year, polls show both Paul and Huntsman earning higher support among undeclared voters than registered Republicans.

Rick Santorum (Mary Ann Chastain/Reuters)

Santorum’s challenge is that while very conservative voters made up nearly half of Iowa caucus-goers last week, they accounted for only one in five participants in the 2008 New Hampshire Republican primary. To finish in the top three, Santorum needs to maximize turnout among strong conservatives and peel as many of their votes away from Mitt Romney and Paul.

Jon Huntsman (Associated Press)

5. Late deciders — Fully 18 percent of Iowa caucus-goers made up their mind on caucus day, and over three in 10 likely primary voters in New Hampshire are either completely undecided or say they could change their mind at the ballot box, according to the latest Suffolk poll. If Santorum’s charge to the top in Iowa is any indication (he won 35 percent among those deciding on the day of the primary), late deciders may swing to the candidate who is “hot.” Huntsman appears to have the most momentum in the Suffolk poll, surging from 7 percent to 16 percent in the past week.

For undecided voters, the order of candidates on the ballot can make a difference. As Post polling director Jon Cohen wrote Tuesday, New Hampshire’s ballot may hurt Romney and Santorum, who appear close to the bottom of the list of 30 candidates.

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