Will Moderate/Conservative Democrats Back Bush or Stay Home if Dean is the Nominee

The liberals on this site love to claim that only Dean can attract the progessive vote (take a look at the Iowa results??) and that if Dean isn't the nominee, many will stay home or vote third-party in protest. This, in theory, is good reason why Dean ought to be the nominee. To keep the progressive vote excited and supportive.

But why don't you all take into account conservative and moderate Democrats who might be turned off by Dean? Won't they be inclined to stay home or vote Bush if he's the nominee. Or does it only work the other way around??

Curious.