Trump has cruised along this election season with around 30-35 percent of the R primary voters.  In the currently divided field, that is all he has needed.  In NH, Trump had 35% in a field of nine with his closest competition 19% behind (Kasich).  Others (Cruz, Rubio, and Bush) trailed him by roughly 24%.  In SC, Trump drew 32% of the voters in a six person race; while his closest rivals were only 10 percentage points behind him (Rubio and Cruz at 22%).  He again trounced the laggers (Carson, Bush, Kasich) who hovered about 8% by about 25 percentage points.

Trump’s support remains solid.  But, as the field narrows his lead shrinks. Cruz and Rubio are like bad rashes, they are not going away.  That leaves, in some sense, the fate of The Donald and the Rs in the hands of Bush, Kasich, and Carson.

Bush has now stepped out.  One can expect some small proportion of his voters to go to Trump, but most will migrate to Rubio or Kasich. If Kasich leaves, then his voters are likely to go largely to Rubio, with piddling amounts to Cruz or Trump.  If Carson decides he has sold enough of his biographies and decides to leave or just to go change clothes, then most of his his voters will be likely to go to Bible thumping Cruz with some to the outsider Trump and a splash to Rubio.

So, what would SC have looked like if it were a three person race (Yes, this is wildly imaginative and potentially wildly wrong, but no less fun)

TRUMP —  32 + 1 (Bush peeps) + 1 (Kasich peeps) + 2 (Carson peeps) =  36

RUBIO  —  22 + 6 (Bush peeps) + 6 (Kasich peeps) + 1 (Carson peeps) =   33

CRUZ  —     22 + 1 (Bush peeps) + 1 (Kasich peeps) + 5 (Carson peeps) =  29

Neither Cruz nor Rubio are leaving this election until the bell ending the last round has sounded. That makes the final question–what do the Rs do with a brokered convention?

At that point, I think Rubio probably wins, and the big question is whether Trump decides he is so pissed that he does a third party bid (Please, Lord, Make It So!).

If he threatens a third party run in a brokered convention (and he certainly will threaten), then the question is what do the Rs do.

Do they bite the bullet and lose the party, the Senate, and the Presidency with Trump and get rid of his ass once and for all (I doubt he would be up for 2020 if he goes in 2016 and loses) and bank on 2020?

Or, do they bite a different bullet for 2016, go for Rubio, keep some Senate seats, and accept the possibility of Trump entering the race without them, and hope he then disappears and lets them have their one-third of their party back.

The basic reality underlying all of this is that Trump basically has about a third of Republican primary voters, and he will keep them for as long as he has a political breath. The Rs will have to deal with that.  How they do it is the real open question.