Romney won the Nevada caucus with a commanding lead over his rivals coming in a full 30 points ahead of Gingrich (49.7 for Mitt, 20 for Newt) and Santorum came in last pulling 10%. Demographically Romney won, well, almost everything. Notably he didn't win the young (Ron Paul), He didn't win <30k income (Newt), and he only barely won Protestant/Other Christian and super Tea Party supporters. Elsewhere, both Newt and Santorum combined usually didn't beat Romney.
This poses an interesting question: who ought to drop out?
Who Ought To Drop Out?
Well, obviously the answer is that "nobody has to." Newt has angered Santorum suggesting (kinda) that he ought to drop. Since Newt has made it personal with Romney it doesn't sound like he's going to quit (apparently Sheldon Adelson, Gingrich's money-man is happy to keep funding him for now and may switch to Romney in the general if it doesn't work ...). Likewise, Santorum has gotten an endorsement from the evangelicals--a key constituency--and he's yet to be really beat up during the primary so he's probably not looking to quit. Why does anyone have to?
The reason someone "ought" to drop out is that so long as both Newt and Rick split the ABR (anybody-but-Romney) vote Romney cruises to the nomination. If you fear for the soul of the GOP you want a single challenger. Neither man is perfect for this--but (outside of Nevada) if you add them together (Ron Paul's vote is not really on the table) then you do get a Romney killer ... assuming one gets the other's vote.
So the question still remains: who 'ought' to leave. Let's look!
Clearly It Should Be Santorum!
Rick Santorum has 8 delegates to Newt's 25 to Romney's 77. You need 1144 to win--but hey, he's in last place, eh? On InTrade the odds on Santorum taking the nomination are a measly 3.4%--that seems pretty low. Plus, after Iowa he's been pretty much last place. He's not taking off and he doesn't have much money.
(I'm not sure how current this is--it came from MotherJones--but it makes the point).
Although polling is not strong for him, by RCP average he loses to Obama by 9 points: outside the likely margins of error. If you want an Obama-killer: it ain't him. And, let's remember, he hasn't even been vetted yet. Santorum has never held first-place so neither Romney's super-guns nor the liberal media have decided to destroy him. While he may not have much in the closet he's a gamble: what if he's the last-man-standing and it turns out he has some major weakness? At least with everyone else ... you know the score.
Finally, Santorum is certainly not the heir to the Tea Party's GOP! He has no executive experience and is not especially fiscally conservative by record (he has been described as a big government guy who really hates gays and abortion).
Are You Crazy!? It Can't Be Santorum!!
On the other hand, Santorum is favored to win the Minnesota caucus. That's not nothing. According to the most recent Rasmussen Poll he's up by +1 over Obama! Maybe it's a trend? The real reason it can't be Santorum, though, is that he doesn't have the baggage. By all appearances he's a family man (more than can be said of Gingrich who is, at best, a families man). He may not have been vetted but he seems to lead a pretty clean, pretty transparent life.
And here's the big deal: his voters are, by and large, family-values evangelicals. The problem is that if he drops his peeps may not be able to go to Gingrich. Oh, sure, they don't want a Mormon (maybe)--and they don't really want Romney (definitely)--but this is the 21st century. Mormonism may not really be their kind of Christianity but Romney's moral character simply isn't in question (unless you count Bain Capital--which we do not for these purposes).
Gingrich's character, on the other hand, is all too well known: unless you want a 'First Mistress' in the White House you have to go somewhere else. If Santorum drops his vote might go to Romney.
So Clearly It Should Be Newt?
Newt's chances against Obama average in at a staggering +12. Gingrich seems poised to lose women the way he did in Florida--which would be suicide in the general. Sure, he has a strong backer--but he's being a sore loser and that's a terrible banner for the party. Furthermore, as said above, Newt is carrying the super Tea-Party vote ... but they'll go to Santorum, won't they? Santorum's vote simply won't go to Gingrich.
Finally, look at the candidate's favorability ratings! Gingrich is -35 to Santorum's, like, -6. C'mon, man--what are you thinking?
Clearly Gingrich should drop out.
Are You Nuts!? It Can't Be Newt!!
The reason Newt is doing so well is because he's an attack dog. Santorum has shown some ability to attack but nothing like Newt. Oh, sure he has negative favorability ratings but Romney has been crashing too. Newt has funding (or, at least, has had funding) and has the experience needed to be president. Plus, Newt will chew up Obama in the debates (assuming that Obama doesn't lie--because apparently dishonesty is the secret super-weapon to debating, I hear).
And consider this: Newt holds most of the ABR voters right now. Sure, they might go to Last-Man-Santorum ... but what if they like Newt because they think he's a fighter. What if that portion went to Ron Paul instead? Consider the down-side.
What Do I Think?
I think the argument that Santorum's voters might go to Romney is actually the strongest one here. We assume that once the mud-slinging stops all those negative favorability ratings will improve somewhat but Newt is then still in deep water. I do think that Santorum's anti-gay stance is going to make it easy to paint him as a caveman in terms of the electorate but while there's not a lot you can do about that there's even less you can do about Newt Gingrich's past.
If I were a GOP strategist with command/control power over the candidates I would, because of the polling, pretty much have to choose Romney as the front-runner no matter how damaged I thought he was. By the latest RCP Polling he's only 2.2 under Obama.
The fact of the matter is that this election is going to heavily hinge on what happens during the summer. If (a) the Euro collapses or Greece goes down (likely), (b) Gas hits $5.00 / gallon and the recovery stalls, or (c) Israel attacks Iran (or there is a war or significant action in the straits) then it seems likely that the Obama presidency will be all but done for.
As those events are largely outside of American control what the GOP needs is someone who is semi-legitimate to sweep up the wreckage. Romney certainly fits that bill and Newt and Santorum arguably do not. On the basis of risk-mitigation I would want to have Romney positioned as a vote of last resort. If, on the other hand, the economy keeps adding 150k jobs per month (and, remember, people who drop out of the labor force count as jobs added!) then it's probably not going to matter too much who I run since Obama will likely win if a recovery takes hold.