So what are the best case scenarios for each candidate out of Iowa? Here's how I see it.
Clark
The general doesn't want Gephardt mucking things up, so he wants him out. He also wants a weaker Kerry now that second place in NH is a real possibility. He also doesn't want Edwards to gain any traction.
Given that Clark needs to get this down to a two-man race as soon as possible, his best outcome is a solid, convincing Dean victory. It would knock out Gephardt and deal a fatal blow to Kerry. And while Dean would be strengthened, Clark has no chance of winning NH anyway. He doesn't need to win NH. That second-place finish will set him up just nicely heading into the February 2 states.
Oh, and Edwards under the 15 percent mark wouldn't hurt.
Dean
Dean needs Gephardt out, and a Kerry and Edwards strong enough to help split the ABD vote.
So we're talking a solid victory, but with a strong second-place showing for Kerry that would garner positive "comeback kid" press. A strong third place by Edwards would be gravy -- giving him momentum in SC that would cause Clark's people nothing but headaches.
Edwards
Edwards has some momentum of late, and he needs to keep it up to validate his "turtle and the hare" strategy. He's got to know that an Iowa victory is all but impossible. But he doesn't need it. A strong third or fourth with some delegates in his pocket would suit him.
More important to Edwdards would be halting some of Clark's momentum. And no one can do that better than Kerry. A strong Kerry showing would knock Clark down a peg or two in NH, and kill some of that all-important momentum heading into the February 2 states, where Edwards has to make his move.
So, Edwards needs a third- or strong fourth-place finish, and a Kerry victory or strong second-place finish.
Gephardt
Needs a win. It's the only way he lives to fight another day.
Kerry
Kerry is in a bind. When the race was neck and neck in NH, a strong Iowa finish may have been enough to propell Kerry into the lead in NH. But now he would have to leapfrog two candidates -- Clark and Dean.
And Clark has free rein in NH, which he's using to stomp all over Kerry.
A strong second-place finish would garner Kerry good press and maybe even some "comeback kid" talk. While that might be enough to best Clark, it's hard to see how it would be enough to get him by Dean assuming Dean won Iowa.
So Kerry needs either a win, or a strong second-place finish and a Gephardt victory.
Lieberman
Ol' Joe needs to be the last man standing next to Dean to have a chance (what little of it he might have). So he needs a strong Dean finish, killing Gephardt, and a strong second-place finish for Kerry. That would allow Kerry to dent Clark's momentum in NH. He'd also like to see Edwards flounder in IA.
That way, the NH primary features a strong Dean, a vicious Clark/Kerry battle for second, and a weak Edwards. Lieberman might slip in and steal a second or third place finish. Since he's a weak candidate, he needs to bring down the non-Dean opposition to his level.