I found this study from the Pew Forum interesting: The drop in Bush’s popularity among younger evangelicals is more precipitous than among older evangelicals.
Similarly, younger evangelicals are less likely to describe themselves as Republican than they were just a couple years ago.
I wonder if this helps explain, to some degree, the Huckabee effect among young voters in evangelical-dominated Iowa and South Carolina. In Iowa, Huckabee outperformed Romney, Thompson, McCain, Giuliani and Hunter combined among voters under 30. In South Carolina, Huckabee was the top vote-getter among voters under 45. Huckabee is widely viewed as a different kind of Republican because of his emphasis on racial justice, reigning in corporate corruption, and taking care of the environment. Also, note that the Pew Forum found that younger white evangelicals are even more conservative than their older counterparts on abortion, and Huckabee is clearly the most pro-life of all the candidates.
(HT: Jonathan Dodson)