The GOPe is really not thinking it through with their swing to Trump

I swear that GOP establishment has had a brain tumor for breakfast (stole that line from "Heathers") and has for the last few weeks.  I understand why they hate Cruz, basically, he doesn't like them and won't give them jobs in the White House even if he wins.  So based on their calculus, if he loses they lose and if he wins, they lose.  So in opposing Cruz they are operating in their own self-interest albeit the self-interest of people who have no true guiding principles but their self-interest nonetheless. 

What I don't get though is why they are piling in with Trump (Dole, Grassley etc.) and against Cruz right before the Iowa caucuses. In my honest opinion as an armchair quarterback and political junkie with no actual political experience, I think that Cruz is stoppable after Iowa but Trump simply isn't.  So let's say Cruz wins in Iowa, the Trump bubble might finally pop and one of the "establishment" candidates might finally get some oxygen for their campaign.  Then the establishment can start their "kill Cruz" campaign and pile into JEB, Christie, Rubio or Kasich, whoever is looking strongest.  They can also pressure the others to drop out so it becomes a one on one contest which would even the playing field a little.  And while the initial calendar does favor Cruz with so many red states voting initially, we are talking a delegate battle and there is a way to stop him from amassing the necessary delegates prior to the convention.  The chance isn't anywhere near 100% but there is a chance to stop him.

Now what if Trump wins Iowa?  Then he gets a momentum boost in NH and then that boost helps him pretty much run the table in most states and then we are stuck with Donald Trump as the nominee.  I realize many in the establishment would prefer Trump to Cruz but wouldn't they rather have Rubio or Christie instead?

What they should be doing is piling onto Trump right now, letting everyone know all of the horrible comments he has made over the years to really chip away at any evangelicals who are behind him now.  Then once his bubble is popped (hopefully), THEN they should turn on Cruz to try to get one of their own elected.  Seriously, are these people complete morons?