If you look around FR you’ll see the pro Gingrich crowd already warming up to destroy Santorum while proclaiming Newt to be a saint.
It's all going to depend on how effective Romney's attacks are against Santorum. If Santorum holds up, then he'll likely hang on to the "anti-Romney" movement. If Romney's shots hit home, then some of those folks who shifted from Newt to Santorum may shift back to Newt.
But for Newt himself to go after Santorum would be suicide. He needs Romney to do that dirty work if he still wants to win, and honestly, I think Gingrich is sufficiently vindictive that his support for Santorum over Romney is genuine. But, he'd still like to win himself, so he's not pulling out.
Well, have at it, I guess.
If FR could have brought down Romney by now, it would have. So we’ll see if there’s more success at bringing down a real conservative.
Just the nature of politics.
Seems to me that people who have not already committed to Newt are very unlikely to unless Santorum stumbles. The problem the Gingrich campaign has with trying to bring out the big guns against Santorum (and, to some extent, Romney) is that Gingrich is the candidate who is MOST vulnerable to effective negative advertising.
I mean: it’s very easy to convey that Gingrich worked with Freddie Mac and conservatives instantly have their own opinion of what that means. But trying to convey that working for a venture capital firm was bad and so on, it’s just not as easy a sell.