Alright, here is my answer to this question.
I think that it really boils down to how deeply you believe we are in a war with terror. Along with that sentiment, how much you believe we are still at risk- and not just any risk, but serious risk.
People that I've talked to seem to fit on a spectrum, where if you believe that we face a serious catastrophic terroristic threat against a potent enemy, you will vote for Bush. The less you feel that way, on a sliding scale, the more you will vote for Kerry.
This is why a number of prominent Democrats/liberals have been supportive of President Bush against their party: Zell Miller, Joe Liebermann, Tony Blair. I'm not saying that they have all bailed on their party, only that they view the war on terror with all seriousness and agree with the President's response to it.
In my opinion, those in favor of other priorities on the domestic front may be sincere, but in my opinion are out of touch with reality. Its all fine and dandy to care about our economy or whatever, but these things won't matter if we are dead. And I do not think that is hyperbole (or not much, anyway). The situation is worse then I think even the Bush Admin is letting on.