Young people like Christie right now because he seems cool, humored about his weight on SNL, and he called out Republicans in Congress for their antics when it came to Hurricane Sandy. Any sort of anti-partisan politics is massively popular with my generation right now, who just want to see things get done. The second Christie panders to the right in a primary, that youth lead and bipartisan image is going to go away so fast that it will neuter any advantage that Republicans would have seen in nominating him.
Christie is dangerous to the Democrats chances in 2016, but he becomes a lot less dangerous if can't win the primary without pandering to the far right, or his pre-Sandy partisan self emerges in a campaign.
What happens in the primaries seems to stay in the primaries. Clinton was very critical of Obama and then her and her supporters joined him. He has great appeal across the aisle. For example, he criticized Jon Corzine for leaving a Bruce Springsteen concert early. Springsteen isn't exactly the most popular among conservatives nor does he care for the Republican Party, but the two of them get along great. He also worked well with Obama to help with Hurricane Sandy. His conservative points should be highlighted if he wants to win the nomination such as wrestling with the teachers' union. Then in the general election, talk about his conservatism in ways that appeals to everyone such as keeping bureaucrats out of your child's education.
