The political "mainstream" in the USA (and presumably most countries with elected governments) swings back and forth like a pendulum. For a while things are more conservative than most people would like, so they eventually abandon their former loyalties to support a more liberal view. Then at some point the government becomes more liberal than most people would like, so it swings back again. I think it's pretty clear that the pendulum was swinging in the conservative direction in the wake of 9/11, if not before.
You don't have to study physics to know what happens if you give a pendulum a big push in the direction it is already going: The amplitude of the pendulum increases, so it swings wide instead of oscillating around the center. I think it's pretty clear that George W. Bush has shoved the pendulum pretty hard in the direction of conservatism.
Regardless of political rhetoric, I think most people want more to have a government that is not their enemy than they want one that is their friend. The wider the swings of the pendulum, the worse life is for everyone except those who thrive on rapid change, on chaos, on political battles, on the swinging of the pendulum. Everyone else is perhaps a little happier when the pendulum is in their direction, but a lot sadder when it swings the other way.
Now, to apply these thoughts to the upcoming US presidential election. Another 4 years of Bush presidency will most likely make the US government the most actively conservative it has been in many decades. It will drive people the Democratic Party in droves. It will give the Democrats the freedom to liberalize their agenda, since they won't be striving so hard to appeal to swing (independent) voters. While this is all good for the liberal voters, it will suck for the conservative ones.
So, the conclusion I feel that I must reach is that conservative voters (with the exception of extreme conservatives) must vote against George W. Bush in the upcoming presidential election.
To vote for Bush would serve them worse than would electing a moderate Democrat. They've gotten their hard line on Afghanistan and Iraq. They've gotten their shift in various policies, some key judicial appointments, and so on. After a moderate Democrat, they can hope to have another Republican president, one who won't send the voters flocking to the Democratic Party. The result might be slightly less conservative impact, but the alternative is a much stronger liberal impact on the government of the United States.
Moderately conservative voters must do what they can to get the Democratic Party to nominate someone moderate. In states like Massachusetts, where independent voters can vote in the primaries, Republicans should quit their party (temporarily) and try to get the Democrats to field a candidate like Clark, rather than Dean. They should make donations to the Democratic candidate of their choice (even if the lesser of several evils). The alternative is a too-liberal president in 2004 (if Bush loses), or a too-liberal president in 2008 and 2012 (if Bush wins).